#include <bits/stdc++.h>

using namespace std;

int main(){
    
    double s, v;
    cin >> s >> v;
    int n = ceil(s / v);
    int ans = 470 - n;
    int HH = ans / 60, MM = ans % 60;
    if(HH < 10){
        cout << 0;
    }
    cout << HH << ":";
    if(MM < 10){
        cout << 0;
    }
    cout << MM;
    
    return 0;
}