七十分，不知道哪错了

#include <bits/stdc++.h>
using namespace std;
int main ()
{
	int s, v, m = 0, h = 0, ansm = 0, ansh = 0;
	cin >> s >> v;
	if (s / v == 0)
	{
		m = s / v;
	}
	else
	{
		m = s / v + 1;
	}
	m += 10;
	while(m != 0)
	{
		if (m / 60 > 0)
		{
			h ++;
			m -= 60;
		}
		else
		{
			break;
		}
	}
	if (h >= 8)
	{
		ansh = 24 + 8 - h - 1;
	}
	else 
	{
		ansh = 8 - h - 1;
	}
	ansm = 60 - m;
	if (ansm < 10)
	{
		cout << ansh << ":" << 0 << ansm;
	}
	else if (ansh < 10)
	{
		cout << 0 <<  ansh << ":" << ansm;
	}
	else
	{
		cout << ansh << ":" << ansm;
	}
	return 0;
}