90分求助，7测试点

#include <iostream> 
using namespace std;
int main()
{
	int a,b,c=0,d=0;
	cin>>a>>b;
	if(a%b!=0) d=d+1;
	d=d+a/b;
	if(d>=60) 
	{
	    for(;d>=60;)
		{
		    c++;
		    d=d-60;	
		}
	}
	if(d>50) 
	{
		d=d-60;
		c++;
	}
	if((7-c)<=0) c=c-24;
	if((7-c)<10) cout<<"0"<<7-c<<":";
	else if((7-c)==0) cout<<"00";
	else if((7-c)>=10) cout<<7-c<<":";
	
	if((50-d)<10) cout<<"0";
	 cout<<50-d;
	return 0;
}