#include <iostream>
using namespace std;
int main() {
	int s, v,t,n;
	int HH, MM;
	cin>> s >> v;
	if (s % v == 0)
		t = s / v;
	else
		t = s / v + 1;
	if (t < 1440) {
		if (t < 50)
		{
			HH = 7;
			MM = 50 - t;
		}
		else {
			n = (t - 50) / 60;
			HH = 7 - n;
			MM = 60 - (t - 50 - n * 60);
		}
		if (MM > 9) {
			cout << 0 << HH << ':' << MM;
		}
		else {
			cout << 0 << HH << ':' << 0 << MM;
		}
	}
	return 0;
}