#include <bits/stdc++.h>
using namespace std;
int main(){
	double s,v,time;
	int finish,goal,hour,minute;
	cin >> s >> v;
	goal = 8 * 60 + 24 * 60;
	time = ceil(s / v * 1.0);
	goal = goal - time;
	if (goal >= 24 * 60){
		goal = goal - 24 * 60;
	}
	hour = goal / 60;
	minute = goal % 60 - 10;
	if (hour < 10){
		if (minute < 10){
			cout << "0" << hour << ":0" << minute;
		}else{
			cout << "0" << hour << ":" << minute;
		}
	}else{
		if (minute < 10){
			cout << hour << ":0" << minute;
		}else{
			cout << hour << ":" << minute;
		}
	}
	return 0;
}