#include<bits/stdc++.h>
using namespace std;
int main (){
	float s,v;
	int t,a,b,daymin;
	daymin=24*60+480;
	cin>>s>>v;
	t=ceil(s/v);
	if(t>=470){
		daymin=daymin-t-10;
		a=24-daymin/60;
		b=daymin%60;
		printf("%02d:%02d",a,b);
	}if(t<470){
		a=7-(t+10)/60;
		b=60-(t+10)%60;
		printf("%02d:%02d",a,b);
	}
	return 0;
}