#include<iostream>
using namespace std;
int main()
{
	int v, s, h, m;
	cin >> s >> v;
	h = 7;
	m = 60;
	double l= s*1.0 / v;
    if (l >= 60){
	    int x=(s/v)/60;
	    if(x>=24)x=x%24;
		h=h-x;
		int t = (s / v) % 60;
		m = m - 10 - t;
		if ((l - (int)l) != 0)m--;
		if(h<0)h=24+h;
	}
	else {
	    
		m = m - (s / v) - 10;
		if ((l - (int)l) != 0)m--;
	}
	if(h<10&&m>=10)
	cout << "0" << h << ":" << m;
	else if(h>=10&&m>=10)
    cout << h << ":" << m;
	else if(h>=10&&m<10)
	cout << h << ":" <<"0"<< m;
	else if(h<10&&m<10)
	cout <<"0"<< h << ":" <<"0"<< m;
	
	return 0;
}

请问是哪里错误，孩子找很久