#include<iostream>
#include<math.h>
using namespace std;
int main(){
	int a,b,c,hour=0,min=0;
	cin>>a>>b;
	c=ceil(((double)a)/b)+10;
	min=c%60;
	hour=c/60+1;
	if(min==0)
	{
		min+=60;
		hour-=1;
	}
	if(c<480)
	{
		cout<<"0"<<8-hour<<":";
		if(min==60) cout<<"00";
		else cout<<60-min;
	}
	else
	{
            hour-=8;
            if(24-hour<10) cout<<"0";
			cout<<24-hour<<":";
			if(min==60) cout<<"00";
			else cout<<60-min;
	}
	return 0; 
}

不知道为什么#3#5输出比标准多1 求调