求修改

#include<bits/stdc++.h>
using namespace std;
int main()
{
	double a,b;
	cin>>a>>b;
	double c=ceil(a/b);
	c=c+10;
	c=480-c;
	int c1=int(c)/60;
	int c2=int(c)%60;
	if(c1<10)cout<<0<<c1;
	else cout<<c1;
	cout<<":"; 
	if(c2<10)cout<<0<<c2;
	else cout<<c2;
    return 0;
}