#include<bits/stdc++.h>
using namespace std;
int main(){
	double s,v;
	cin >> s >> v;
	int t=ceil(s/v);
	int m=470-t;
	int HH,MM;
	HH=m/60;MM=m%60;
	if(HH<10) cout << "0" << HH;else cout << HH;
	cout << ":";
	if(MM<10) cout << "0" << MM;else cout << MM;
	return 0;
}