diff --git a/cv3/program.c b/cv3/program.c
index 5594b67..187564a 100644
--- a/cv3/program.c
+++ b/cv3/program.c
@@ -1,122 +1,107 @@
 #include <ctype.h>
-#include <errno.h>
 #include <stdio.h>
 #include <string.h>
-#include <assert.h>
 #include <stdlib.h>
 
 #define STACK_SIZE 10
 
-struct stack{
+struct stack{                  //definition of STACK struct
     float values[STACK_SIZE];
     int size;
 };
 
-void print_stack(struct stack* stack);
+//function which prints contents of stack
+void print_stack(struct stack* stack); 
+
+//function to append element into stack
 void push_stack(struct stack* stack, float value);
+
+//function to delete last element of stack
 float pop_stack(struct stack* stack);
 
+//function to sum last 2 operands from stack
+void sum(struct stack* stack);
+
+//function to substract last 2 operands from stack
+void substract(struct stack* stack);
+
+//function to multiply last 2 operands from stack
+void multip(struct stack* stack);
+
+//function to divide last 2 operands from stack
+void divis(struct stack* stack);
+
 
 int main(){
     
+    char char_value[STACK_SIZE];      //definition of input array
 
-    char char_value[STACK_SIZE];
-    memset(&char_value,0,STACK_SIZE);
-    float float_value;
-    char* ptr;
-    struct stack myStack;
-    memset(&myStack,0,sizeof(struct stack));
+    memset(&char_value,0,STACK_SIZE); //inicialization of input array
+    
+    float float_value;                //variable to which we convert number from input array (char_value[])
+    char* ptr;                        //return pointer of fgets
+    struct stack myStack;             //struct myStach of type stack
+    memset(&myStack,0,sizeof(struct stack)); //initialization of myStruct structure
     while(1){
-        if(myStack.size == 10){
-            //print_stack(&myStack);
+        if(myStack.size == 10){         //condition to break the cycle if we have full stack
             puts("full stack");
             break;
         }
 
-        
-        
-        
+        //load input into char_value
         ptr = fgets(char_value, STACK_SIZE-1, stdin);
-        if(ptr != NULL){
-
-            if(char_value[0] == '\n'){
+        if(ptr != NULL){                //check if it run ok
+            if(char_value[0] == '\n'){  //if first char is \n, break the cycle, its the end
                 puts("no input");
                 break;
             }
-
-            /*if(char_value[0] == '0'){
-                push_stack(&myStack,0);
-                print_stack(&myStack);
-                printf("\n");
-                continue;
-            }*/
- 
+            
+            //sum
             if(char_value[0] == '+'){
                     if(myStack.size > 1){
-                    float a = pop_stack(&myStack);
-                    float b = pop_stack(&myStack);                    
-                    float c = a+b;
-                    push_stack(&myStack, c);
-                    print_stack(&myStack);
-                    printf("\n");
+                        sum(&myStack);
                     }else{puts("not enough operands"); break;}
-            }else if(char_value[0] == '-'){
+            }
+            
+            //substraction
+            else if(char_value[0] == '-'){
                     if(myStack.size > 1){
-                    float a = pop_stack(&myStack);
-                    float b = pop_stack(&myStack);                    
-                    float c = b-a;
-                    push_stack(&myStack, c);
-                    print_stack(&myStack);
-                    printf("\n");
+                        substract(&myStack);
                     }else{puts("not enough operands"); break;}
-                }else if(char_value[0] == '*'){
+            }
+            
+            //multiplication
+            else if(char_value[0] == '*'){
                     if(myStack.size > 1){
-                    float a = pop_stack(&myStack);
-                    float b = pop_stack(&myStack);                    
-                    float c = a*b;
-                    push_stack(&myStack, c);
-                    print_stack(&myStack);
-                    printf("\n");
+                        multip(&myStack);
                     }else{puts("not enough operands"); break;}
-                } else if(char_value[0] == '/'){
+            }
+            
+            //division
+            else if(char_value[0] == '/'){
                     if(myStack.size > 1){
-                    float a = pop_stack(&myStack);
-                    if(a == 0){
-                        printf("division by zero\n");
-                        break;
-                    }else{
-                        float b = pop_stack(&myStack);                    
-                        float c = b/a;
-                        push_stack(&myStack, c);
-                        print_stack(&myStack);
-                        printf("\n");
-                    }
+                        divis(&myStack);
                     }else{puts("not enough operands"); break;}
-                } else if(isdigit(char_value[0]) != 0 ){
+            } 
+            
+            //if its a number
+            else if(isdigit(char_value[0]) != 0 ){
                     float_value = strtof(char_value, NULL);
-                    //printf("float value: %f\n",float_value);
-                    /*if(float_value == 0){
-                        puts("bad input");
-                        break;*/
-                    //} else {
-                        push_stack(&myStack,float_value);
-                        print_stack(&myStack);
-                        printf("\n");
-                        continue;
-               
-                } else {
-                    puts("bad input");
-                    break;
-                }
-        } else { 
-               //push_stack(&myStack, float_value);
-               //print_stack(&myStack);
-               //printf("\n");
-                puts("no input");
+                    push_stack(&myStack,float_value);
+                    print_stack(&myStack);
+                    printf("\n");
+                    continue;
+            } else {
+                puts("bad input"); //if its not digit nor symbol of operation, break cycle, bad input 
                 break;
             }
 
-        } 
+        //if theres no further input
+        } else { 
+            puts("no input");
+            break;
+        }
+    } 
 
 
     return 0;
@@ -141,3 +126,45 @@ float pop_stack(struct stack* stack){
     return value;
 }
 
+void sum(struct stack* stack){
+    float a = pop_stack(stack);
+    float b = pop_stack(stack);                    
+    float c = a+b;
+    push_stack(stack, c);
+    print_stack(stack);
+    printf("\n");
+}
+
+void substract(struct stack* stack){
+    float a = pop_stack(stack);
+    float b = pop_stack(stack);                    
+    float c = b-a;
+    push_stack(stack, c);
+    print_stack(stack);
+    printf("\n");
+}
+
+void multip(struct stack* stack){
+    float a = pop_stack(stack);
+    float b = pop_stack(stack);                    
+    float c = a*b;
+    push_stack(stack, c);
+    print_stack(stack);
+    printf("\n");
+}
+
+
+
+void divis(struct stack* stack){ 
+    float a = pop_stack(&myStack);
+    if(a == 0){
+        printf("division by zero\n");
+        break;
+    }else{
+        float b = pop_stack(&myStack);                    
+        float c = b/a;
+        push_stack(&myStack, c);
+        print_stack(&myStack);
+        printf("\n");
+    }
+}