#include <iostream>
#include <string>
using namespace std;

int main() {
    int s, v;
    cin >> s >> v;

    int tempMin = s / v + (s % v != 0); 
    tempMin += 10; 

    int min = 8 * 60 - tempMin;

    // 如负，转到前一天
    if (min < 0) {
        min += 24 * 60;
    }

    int hh = min / 60;
    int mm = min % 60;

    cout << (hh < 10 ? "0" : "") << hh << ":" << (mm < 10 ? "0" : "") << mm << endl;

    return 0;
}