#include <iostream>
using namespace std;

int main() {

	int s; 
	cin >> s;//s为从家到学校的路程
	int v; 
	cin >> v;//v为速度
	int t; 
	t = s / v + s % v + 10;//t为全程总消耗时间
	int m, n;//代表时和分

	//1.如果yyy将在前一天出发
	if (t > 480) {
		m = (1440 - t + 480) / 60;
		n = (1440 - t + 480) % 60;
		if (m < 10) {
			if (n == 0) {
				cout << "0" << m << ":00";
			}
			else if (n < 10) {
				cout << "0" << m << ":0" << n;
			}
			else
				cout << "0" << m << ":" << n;
		}
		else{
			if (n == 0) {
				cout << m << ":00";
			}
			else if (n < 10) {
				cout << m << ":0" << n;
			}
			else
				cout << m << ":" << n;
		}
	}
	//2.如果yyy在当天出发
	else {
		m = (480 - t) / 60;
		n = (480 - t) % 60;
		if (m < 10) {
			if (n == 0) {
				cout << "0" << m << ":00";
			}
			else if (n < 10) {
				cout << "0" << m << ":0" << n;
			}
			else
				cout << "0" << m << ":" << n;
		}
		else {
			if (n == 0) {
				cout << m << ":00";
			}
			else if (n < 10) {
				cout << m << ":0" << n;
			}
			else
				cout << m << ":" << n;
		}
	}
	

	return 0;
}