#include<stdio.h>
int main() {
	int s, v;
	int t, time;
	int a, b;
	scanf("%d %d", &s, &v);
	t = (int)(s / v + 1);
	if (t <= 470) {
		time = 480 - 10 - t;
		a = time / 60;
		b = time % 60;
		printf("%02d%c%02d", a, ':', b);
	}
	else {
		t = t - 470;
		int i, j;
		i = t / 60;
		j = t % 60;
		printf("%02d%c%02d", 23 - i, ':', 60 - j);
	}
	return 0;
}