#include <iostream>
#include<iomanip>
#include<cmath>
using namespace std;
  int main()
{
    double s, v;
    cin >> s >> v;
    int t = ceil(s / v);
    int rubbish = 10;
    int T = t + rubbish;
    int hour, minute;
    if (T <= 480)
    {
        hour = 8-ceil((double)(T) / 60);
        minute = 60 - (T % 60);
        cout << "0" << hour << ":" << minute << endl;
    }
    else if (T > 480&&T<1440)
    {
        hour = 24 - (ceil((double)(T) / 60) - 8);
        minute= 60 - (T % 60);
        if (hour < 10)
            cout << "0" << hour << ":" << minute << endl;
        else cout << hour << ":" << minute << endl;
    }
    return 0;
}