diff --git a/a2/program.c b/a2/program.c
index 20a34b9..c44595b 100644
--- a/a2/program.c
+++ b/a2/program.c
@@ -1,6 +1,5 @@
 #include <stdio.h>
 #include <stdlib.h>
-#include <assert.h>
 #include <string.h>
 #include <stdbool.h>
 #include <ctype.h>
@@ -10,6 +9,8 @@ struct stack{
     int size;
 }stack;
 
+///add bracket to stack
+
 void push(char ch){
     if(stack.size < 100){
         stack.size++;
@@ -17,7 +18,9 @@ void push(char ch){
     }
     else
         exit(0);
-} 
+}
+
+///if i have opening bracket in stack, then decrement size
 
 void pop(){
     if(stack.size >= 0)
@@ -26,6 +29,8 @@ void pop(){
         exit(0);
 }
 
+///compare brackets
+
 bool find_pair(char a, char b){
     if(a == '(' && b == ')') 
         return true;
@@ -37,8 +42,10 @@ bool find_pair(char a, char b){
         return true;
 
     return false;
-
 }
+
+///function to find right pair
+
 char right_pair(char a){
     char b;
     if(a == '(')
@@ -53,6 +60,8 @@ char right_pair(char a){
     return b;    
 }
 
+///find the last opening bracket in the stack
+
 char gettop(){
     return stack.data[stack.size];
 }
@@ -69,52 +78,60 @@ int main(){
 
     int l = strlen(line);
     int i, j = -1, f = -1;;
-    char *l_bracket = calloc(l, sizeof(char));
-    char *r_bracket = calloc(l, sizeof(char));
+    char *o_bracket = calloc(l, sizeof(char));
+    char *c_bracket = calloc(l, sizeof(char));
      
     for(i = 0; i < l; i++){
         if(line[i] == '{' || line[i] == '(' || line[i] == '[' || line[i] == '<'){
             push(line[i]);
             j++;
             f++;
-            l_bracket[j] = gettop();
-            r_bracket[f] = right_pair(l_bracket[j]);
+            o_bracket[j] = gettop();                   //get opening bracket from the stack
+            c_bracket[f] = right_pair(o_bracket[j]);   //get closing bracket 
         }
-        if(line[i] == '}' || line[i] == ')' || line[i] == ']' || line[i] == '>'){   
-            if(stack.size == -1){
+        if(line[i] == '}' || line[i] == ')' || line[i] == ']' || line[i] == '>'){
+
+            if(stack.size == -1){                      //if there is no opening bracket in the stack
                 printf("Unexpected closing bracket %c in %d\n", line[i], i);
                 return 0; 
 
             }
-            else if(!find_pair(gettop(), line[i])){
-                printf("Crossed bracket %c in %d, expected %c \n", line[i], i, r_bracket[j]);
+            else if(!find_pair(gettop(), line[i])){    //if there is another closing bracket 
+                printf("Crossed bracket %c in %d, expected %c \n", line[i], i, c_bracket[f]);
                 return 0;            
             }
             else{
-                 r_bracket[f] = 0;
-                 f--;
+                 c_bracket[f] = 0;                     //if closing bracket is correct then reducee array
+                 f--;                                  //if i didn't find a correct bracket, then keep it in the array
                  pop();
             }
         }
     }
    
     int begin = 0;
-    int end = strlen(r_bracket);
+    int end = strlen(c_bracket);
     int temp;
-    //printf("%s", b);
+
+    //now i have all missing closing brackets in array
+ 
+    //flip array
     while(begin < end){
-        temp = r_bracket[begin];
-        r_bracket[begin++] = r_bracket[--end];
-        r_bracket[end] = temp;
+        temp = c_bracket[begin];
+        c_bracket[begin++] = c_bracket[--end];
+        c_bracket[end] = temp;
     }
 
+    //if program pop all opening brackets from the stack, then stack size must be -1;
     if(stack.size == -1){
         printf("All brackets OK\n");
     }
+    //if no, then program didn't find closing bracket
     else {
-        printf("Missing closing brackets: %s\n", r_bracket);        
+        printf("Missing closing brackets: %s\n", c_bracket);        
     }
-    free(l_bracket);
-    free(r_bracket);
+
+    free(o_bracket);
+    free(c_bracket);
+    
     return 0;
 }
diff --git a/cv1/program.c b/cv1/program.c
index 8076ce1..60ed375 100644
--- a/cv1/program.c
+++ b/cv1/program.c
@@ -30,26 +30,31 @@ int read_pizza(struct pizza* item){
 }
 
 int search_string(const char* heap, const char* needle){
+
     int H = strlen(heap);
     int N = strlen(needle);
-    int i;
+    int i = 0;
     for(i = 0; i <= H - N; i++){
         int j;
+
         for(j = 0; j < N; j++){
             if(heap[i+j] != needle[j]){
-                return -1;
-            }
-            if(j = N){
-                return i;    
+                break;
             }
         }
-    } 
+        if(j == N){
+            return i;
+
+        }
+    }
+    return -1;
 }
 
+
 char hacker_script(char c){
     if(isupper(c)){
-        c = tolower(c);    
-    }       
+        c = tolower(c);
+    }
     char numbers[] = "0123456789";
     char letters[] = "oizeasbtbq";
     int i;
@@ -59,48 +64,54 @@ char hacker_script(char c){
             return c;
         }
     }
+    return c;
 }
 
+
 int main(){
     
     printf("Zadaj hladanu surovinu:");
     char key[LINESIZE];
     memset(key,0,LINESIZE);
-    char* r = fgets(key,LINESIZE,stdin);  
-    
+    char* r = fgets(key,LINESIZE,stdin);
+    key[strlen(key)-1] = '\0';
+    int k = 0;
+    for(k = 0; k < strlen(key); k++){
+        key[k] = hacker_script(key[k]);
+    }
+
     printf("Zadaj jedalny listok:");
     struct pizza jedalny_listok[100];
     struct pizza pomocny[100];
     memset(pomocny, 0, sizeof(struct pizza)*100);
-    memset(jedalny_listok, 0,sizeof(struct pizza)*100);    
+    memset(jedalny_listok, 0,sizeof(struct pizza)*100);
     struct pizza item;
     int counter = 0;
+
    
     
-    while(read_pizza(&item)){
+    while(stdin,read_pizza(&item)){
         strcpy(jedalny_listok[counter].name, item.name);
         jedalny_listok[counter].prize = item.prize;
         counter++;
     }
+
     int i, j, f;
+    int i, j;
     for(i = 0; i < counter; i++){
         for(j = 0; j < strlen(jedalny_listok[i].name); j++){
             pomocny[i].name[j] = hacker_script(jedalny_listok[i].name[j]);
-            //printf("%c", pomocny[i].name[j]);
-                 
-        } 
-        search_string(pomocny[i].name, key); 
-        if(search_string(pomocny[i].name, key) != -1){
+
+        }
+        int result = search_string(pomocny[i].name, key);
+        if(result != -1){
             printf("%s", jedalny_listok[i].name);
             printf("%.2f\n", jedalny_listok[i].prize);
-            printf("Nacitano %d poloziek.\n", counter);
-            return 1;        
-        }       
-     
-    }
-    printf("Nacitano %d poloziek\n", counter);
-    return 1;    
-   
-}
+        }
 
-  
+    }
+    printf("Nacitanych %d poloziek.\n", counter);
+    return 0;
+
+
+}  
diff --git a/cv2/program.c b/cv2/program.c
index 9798c01..fe26dbb 100644
--- a/cv2/program.c
+++ b/cv2/program.c
@@ -2,7 +2,6 @@
 #include <string.h>
 #include <stdlib.h>
 
-
 #define LINESIZE 100
 
 struct pizza{
@@ -10,6 +9,9 @@ struct pizza{
     float prize;
 };
 
+//read the name and prize
+//push them to stack
+
 int read_pizza(struct pizza* item){
    
     char line1[LINESIZE];
@@ -30,20 +32,17 @@ int read_pizza(struct pizza* item){
         return 1;   
     }   
 }
-int comparename(const void *a, const void *b){
-    
-    struct pizza* pizza_a = (void*) a;
-    struct pizza* pizza_b = (void*) b;
 
-    return strcmp(pizza_a->name, pizza_b->name);
-    
-}
-int compareprize(const void *a, const void *b){
-    
+//compare 2 elements
+
+int compare(const void *a, const void *b){
+
     struct pizza* pizza_a = (void*) a;
     struct pizza* pizza_b = (void*) b;
-       
     float r = (pizza_a->prize > pizza_b->prize) - (pizza_a->prize < pizza_b->prize);
+    if (r == 0){  //if prizes are identical, than check if names are in alphabetical order
+        r = strcmp(pizza_a->name, pizza_b->name);
+    }
     return r;
 }
 
@@ -55,23 +54,20 @@ int main(){
     struct pizza item;
     int counter = 0;   
     
+    //write menu to array
     while(stdin, read_pizza(&item)){
         strcpy(jedalny_listok[counter].name, item.name);
         jedalny_listok[counter].prize = item.prize;
         counter++;
     }
-   
-    qsort(jedalny_listok, counter, sizeof(struct pizza), compareprize);
-    
-    //qsort(jedalny_listok, counter, sizeof(struct pizza), comparename);    
 
+    qsort(jedalny_listok, counter, sizeof(struct pizza), compare);
+    
     int i = 0;
     for(i = 0; i < counter; i++){
         printf("%s", jedalny_listok[i].name);
         printf("%f", jedalny_listok[i].prize);
         printf("\n");
     }
- 
-
     return 0;
 }
diff --git a/cv3/program.c b/cv3/program.c
index 9f39b2b..73ca78b 100644
--- a/cv3/program.c
+++ b/cv3/program.c
@@ -1,27 +1,43 @@
-#include <assert.h> 
 #include <stdio.h> 
 #include <stdlib.h>
 #include <string.h>
+#include <ctype.h>
 
-#define STACK_SIZE 100
+#define STACK_SIZE 10
 
 struct stack {
     float values[STACK_SIZE];
     int size;
 };
 
+//push number to the stack
+
 void push(struct stack* stack,float values){
-    assert(stack->size < STACK_SIZE);
-    stack->values[stack->size] = values;
-    stack->size += 1;
+    if(stack->size < 10){
+        stack->values[stack->size] = values;
+        stack->size += 1;   
+    }
+    else{
+        printf("full stack\n");
+        exit(0);
+
+    }
 }
 
+//pop number from the stack
+
 float pop(struct stack *stack){
-    assert(stack->size > 0);
-    float values = stack->values[stack->size-1]; 
-    stack->size -= 1; 
-    return values; 
+    if(stack->size > 0){
+        float value = stack->values[stack->size-1];
+        stack->size -= 1;
+        return value;
+    }
+    else{
+        printf("not enough operands\n");
+        exit(0);
+    }
 }
+
 void print_stack(struct stack *stack){
     int i;
     int len = stack->size - 1;
@@ -30,9 +46,8 @@ void print_stack(struct stack *stack){
     }
     if(stack->size != 0){
         printf("%0.2f ", stack->values[i]);
-    }
-    printf("\n");
-
+        printf("\n");
+    }   
 }
 
 
@@ -40,44 +55,57 @@ int main() {
     struct stack mystack;
     memset(&mystack, 0, sizeof(struct stack));
     int i = 0;
-    float z;
-    for(i = 0; i < 10000; i++){
+    for(i = 0; i < 100; i++){
+
         char line[10];
         char *x = fgets(line, 10, stdin);
         float r = 0;
-         
-        if(!isdigit(line[0]) && line[0] != '+' && line[0] != '*' && line[0] != '/' && line[0] != '-'){
-            printf("no input");
-            return 0;
-        }       
+        float z = 0;
         
-        if(line[0] == '+'){
-            r = pop(&mystack) + pop(&mystack); 
-        }
-        else if(line[0] == '-'){
-            z = pop(&mystack);
-            r = pop(&mystack) - z;
-        }
-        else if(line[0] == '*'){
-            r = pop(&mystack) * pop(&mystack);
-        }
-        else if(line[0] == '/'){
-            z = pop(&mystack);
-            if(z != 0.0){
-                r = pop(&mystack) / z;
+        //if string is not empty
+        if(line[1] != 0 && x != NULL){
+
+            //if there is a wrong symbol
+            if(!isdigit(line[0]) && line[0] != '+' && line[0] != '*' && line[0] != '/' && line[0] != '-'){
+                printf("bad input\n");
+                return 0;
+            }       
+
+            if(line[0] == '+'){
+                r = pop(&mystack) + pop(&mystack);
             }
-        }
-
-        else {
-            r = strtof(line,&x);
-        }      
+            else if(line[0] == '-'){
+                z = pop(&mystack);   //swap numbers(e.g input "3 4 -"
+                r = pop(&mystack) - z;            //output 3 - 4, not 4 - 3)
+            }
+            else if(line[0] == '*'){
+                r = pop(&mystack) * pop(&mystack);
+            }
+            else if(line[0] == '/'){
+                z = pop(&mystack);
+                if(z == 0){
+                    printf("division by zero\n");
+                    return 0;
+                }
+                else {
+                    r = pop(&mystack) / z;
+                }
+            }
+            //if symbol is not operation, than it is number
+            //change string to float
+            else {
+                r = strtof(line,&x);
+            } 
+            //push result to stack
+            push(&mystack,r);
         
-        push(&mystack,r);
-        print_stack(&mystack);
-            
+            print_stack(&mystack);
+        }
+        else{
+            printf("no input\n");
+            return 0;
+        }    
     }
-
-
-
+      
     return 0;
 }