یک ساعت

main.c

#include <iostream>

using namespace std;

int main()
{
    int a,b;
    
    cin >> a >> b;
    
   if ( a > 12 && a < 24){
       a = a - 12;
        if ( b != 0){
                b = 60 - b;
       }
       
   }else if ( a < 12 && a != 0){
       a = 12 - a;
      if (b != 0 && a != 6){
          b = 60 - b;
      }
   }else if ( a == 12 ) {
       a = 12 - a;
       if ( b != 0){
                b = 60 - b;
       }
  
   }else if ( a == 24 ) {
       a = 0;
   }else if (a == 0){
      if ( b != 0){
                b = 60 - b;
       }
       
   }
   
   string h = a > 9 ? to_string(a) : "0" + to_string(a);
   string m = b > 9 ? to_string(b) : "0" + to_string(b);
   
   
   cout << h << ":" << m;
   
   return 0;
}