#include <iostream>
#include <cmath>
using namespace std;
float s,v;
int main(){

    cin >> s >> v;
    int time = ceil(s/v);

    int number = 470;
    int losetime;
    losetime = number - time;

    if(losetime > 0){
        cout << "0";
        cout << losetime / 60<<":";
        if(losetime % 60 != 0){
                cout << losetime % 60;
        }else{
            cout <<"00";
        }
        return 0;
    }else if(losetime < 0){
        losetime = 1440 + losetime; 
        if(losetime / 60 < 10){
            cout << "0";
        }
        if(losetime > 480){
            cout << losetime / 60 << ":";
            if(losetime % 60 != 0){
                cout << losetime % 60; 
            }else{
                cout << "00";
            }
        }else{
            cout << "8:00";

        }
        return 0;
    }else if(losetime == 0){
        cout << "00:00";
        return 0;
    }
    return 0;
}