#include<iostream>
#include<cstdio>
using namespace std;
int main() {
	int s, v, hour, min, need;
	int t = 0;
	cin >> s >> v;
	if (s/v != 0)
		t = s / v + 1;
	else
		t = s / v;
	hour = ((8 * 60) - (t + 10)) / 60;
	need = 60 * 8;
	min = ((8 * 60) - (t + 10)) % 60;
	
	if (60 * hour + min <= need * 60)
		printf("%02d:%02d", hour, min);
	else
	{
		hour = ((24 * 60) - (60 * hour + min)) / 60;
		min = ((24 * 60) - (60 * hour + min)) % 60;
		printf("%02d:%02d", hour, min);
	}
	return 0;
}