#include<bits/stdc++.h>
using namespace std;
const int N=1e6+5;
const int M=5050;
signed main ()
{
	int u,s;
	cin>>s>>u;
	int sj;
	sj=ceil(s/u)+10;
	int xiaoshi=8,fenzhong=0;
	fenzhong-=sj;
	while(fenzhong<0){
		fenzhong+=60;
		xiaoshi-=1;
	}
	if(xiaoshi<10){
		cout<<0<<xiaoshi<<':';
	}else cout<<xiaoshi<<':';
	if(fenzhong<10){
		cout<<0<<fenzhong-1;
	}else cout<<fenzhong-1;
	return 0;
}