diff --git a/a1/program.c b/a1/program.c
index 80dcafa..a8d341f 100644
--- a/a1/program.c
+++ b/a1/program.c
@@ -1 +1,162 @@
-////////
\ No newline at end of file
+#include <stdio.h>
+#include <assert.h>
+#include <stdlib.h>
+#include <ctype.h>
+//// @ 
+#define STACK_SIZE 200
+
+struct Stack
+{
+   char values[STACK_SIZE];
+   int size;
+};
+
+void push_stack(struct Stack* stack, float value);
+char pop_stack(struct Stack* stack);
+int count_stack(struct Stack* stack);
+
+
+void push_stack(struct Stack* stack, char value)
+{
+    assert(stack->size < STACK_SIZE); 
+    stack->values[stack->size] = value;
+    stack->size += 1;
+}
+char pop_stack(struct Stack* stack)
+{
+    assert(stack->size > 0); 
+    char value = stack->values[stack->size-1];
+    stack->size -= 1;
+    return value;
+}
+int count_stack(struct Stack* stack)
+{
+  return stack->size;
+}
+
+void print_stack(struct Stack* stack)
+{
+    for (int i=0; i<stack->size; i++)
+    {
+        printf("%.2f ", stack->values[i]);
+    }
+    printf("\n");
+}
+
+char para(char c)
+{
+    if(c=='(') return ')';
+    if(c=='<') return '>';
+    if(c=='{') return '}';
+    if(c=='[') return ']';
+
+    if(c==')') return '(';
+    if(c=='>') return '<';
+    if(c=='}') return '{';
+    if(c==']') return '[';
+}
+
+int main()
+{
+    struct Stack mystack;
+    mystack.size=0;
+
+    char str[128];
+    scanf("%s", str);
+    printf("Read: %s", str);
+
+    int i=0;
+    char c, cs;
+    while(str[i]!='\0')
+    {
+        c=str[i];
+        if(c=='<'||c=='('||c=='{'||c=='[')
+        {
+           push_stack(&mystack, c); 
+        }
+        if(c=='>')
+        {
+            cs=pop_stack(&mystack);
+            if(cs!='<')
+            {
+                printf("Crossed bracket %c in %d, expected %c", c, i);
+            }
+        }
+
+    }
+    
+
+
+
+
+
+
+    int err=0;
+
+    char buf[505];
+
+    do
+    {        
+      char* p=fgets(buf, 299, stdin);    
+      if(p)
+      {
+          char c=buf[0];
+          float op1, op2, rez;
+          if(c=='+'||c=='-'||c=='/'||c=='*')  
+          {
+              if(count_stack(&mystack)<2)
+              {
+                  printf("not enough operands\n");
+                  err=3;
+                  break;
+              }
+              op2=pop_stack(&mystack);
+              op1=pop_stack(&mystack);
+              switch(c)
+              {
+                  case '+': rez=op1+op2; break;
+                  case '-': rez=op1-op2; break;
+                  case '/': 
+                            if(c=='/' && op2==0) 
+                            {
+                                err=1;
+                                printf("division by zero\n");  
+                            }
+                            else
+                                rez=op1/op2;
+                            break;
+                  case '*': rez=op1*op2; break;
+              }              
+          }
+          else 
+          {
+              if(isdigit(c))
+              {
+                rez=atof(buf);
+              }
+              else
+              {
+                err=1;
+                printf("bad input\n");
+              }
+          }
+          
+          if(!err)
+          {
+             if(count_stack(&mystack)==STACK_SIZE)  
+             {
+                 printf("full stack\n");
+                 err=4;
+                 break;
+             }
+            push_stack(&mystack, rez); 
+            print_stack(&mystack);
+          }
+      }  
+      else break;
+
+    }while(1);
+    if(!err)
+        printf("no input\n");
+	return 0;
+}
\ No newline at end of file