#include<bits/stdc++.h>
using namespace std;
int s,v;
int main()
{
	scanf("%d%d",&s,&v);
	int minutes,hours;
	minutes=ceil(1.0*s/v);
	int minutess=(s/v)+10;
	hours=(minutess/60)+1;
	minutess=minutes%60;
	if(hours>=8) printf("%02d:%02d",24+8-hours,60-minutess-10);
	//cout<<hours<<endl;
	else printf("%02d:%02d",8-hours,60-minutess-10);
	return 0;
}

第四个点和第七个点错了