#include <bits/stdc++.h>
using namespace std;

int main() {
	int s, v, h = 8, m = 60, ht, mt;
	cin >> s >> v;
	mt = s / v + 1 + 10;
	ht = mt / 60;
	mt %= 60;
	if (mt == 0) {
		m = 0;
	} else {
		h--;
		m -= mt;
	}
	if (ht >= 8) {
		h += 24;
	}
	h = h - ht;
	printf("%.2d", h);
	cout << ":";
	printf("%.2d", m);
	return 0;
}