Clock

# include <iostream>
using namespace std;
#include <iomanip>
#include <math.h>
#include <cmath>

int main()
{
    int hour;
    int minutes;


    do
    {
        cin.clear();
        cin >> hour;
    } while (cin.bad() || hour < 0 || hour> 23);

    do
    {
        cin.clear();
        cin >> minutes;
    } while (cin.bad() || minutes < 0 || minutes> 59);

    int allinminutes = hour * 60 + minutes+15;
    int futurehour = round(allinminutes/60);
    int futureminute = round(allinminutes - round(futurehour*60));
    if (futurehour > 23)
    {
        futurehour -= 24;
    }

      if (futureminute < 10)
    {
        cout << futurehour << ":0" << futureminute << endl;
    }
    else
    {
        cout << futurehour << ":" << futureminute << endl;
    }
    return 0;
}