测试点#8 #9 #10不过

#include <bits/stdc++.h>
using namespace std;
#define pi ((double) 3.14)

int main()
{
	ios :: sync_with_stdio(false);
	cin.tie(0);
	cout.tie(0);
	int s, v;
	cin >> s >> v;
	int time = 8 * 60 - ceil(double (1.0) * s / v);
	time -= 10;
	if (time < 0)
		time += 24 * 20;
	int hour = time / 60, minute = time % 60;
	if (hour < 10)
		cout << 0;
	cout << hour << ":";
	if (minute < 10)
		cout << 0;
	cout << minute << endl;
	return 0;
}