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

int main() {
	double s, v, c;//c为时间
	int h = 8, m = 60, d, l;//d为走了多少小时，l代表走了多少分钟，h和m分别为时与分
	cin >> s >> v;
	c = s / v;//下面是七点时段，else是如果超出了七点部分
	if (c <= 50) {
		l = floor(50 - c);
		if (l == 0)
			cout << "07" << ":" << "00" << endl;
		else
			cout << "07" << ":" << l << endl;
	} else { 
		l = fabs(floor(50 - c));
		if (l / 60 <= 6) {
			h = h - 2 - (l / 60);
			m -= l % 60;
			if (m == 60) {
				h = h + 1;
				m = 0;//分钟为60进1
			}
			if (m < 10)
				cout << "0" << h << ":" << "0" << m << endl;
			else
				cout << "0" << h << ":" << m << endl;
		} else {
			h = 30 - (l / 60);
			m -= l % 60;
			if (m == 60) {
				h = h + 1;
				m = 0;//分钟为60进1；
			}
			if (m < 10 && h >= 10)
				cout  << h << ":" << "0" << m << endl;
			if (m < 10 && h < 10)
				cout  << "0" << h << ":" << "0" << m << endl;
			if (m >= 10 && h >= 10)
				cout  << h << ":"  << m << endl;
			if (m >= 10 && h < 10)
				cout << "0" << h << ":"  << m << endl;

		}
	}
	return 0;
}