#include <bits/stdc++.h>
using namespace std;
double s, v, t;
int m, h;
int ch = 8, cm = 0;
int main(){
	cin >> s >> v;
	t = 10 + ceil(s / v);
	//cout << t << endl;
	//m = (int)(t);
	//cout << m << endl;
	h = t / 60; m = (int)(t) % 60;
	//cout << h << " : " << m << endl;
	cm -= m;
	ch -= h;
	if(cm < 0){
		ch -= 1; cm += 60;
	}
	//cout << ch <<":" << cm << endl;
	if(ch <= -16){
		ch = 8; cm = 0;
	}else if(ch <= 0){
		ch += 24;
	}
	if(ch < 10){
		cout << "0";
	}
	cout << ch;
	cout << ":";
	if(cm < 10) cout << "0";
	cout << cm << endl;
	return 0;
}