#include<bits/stdc++.h>
using namespace std;
int main(){
	long long s,v,t;
	cin>>s>>v;
	t=s/v+10;
	if(t>480){
		if(t>1320){
			if((t-480)%60<10)cout<<0<<24-(t-480)/60<<":"<<0<<(t-480)%60-1;
			else cout<<0<<24-(t-480)/60<<":"<<(t-480)%60-1;
		}
		else{
			if((t-480)%60<10)cout<<24-(t-480)/60<<":"<<0<<(t-480)%60-1;
			else cout<<24-(t-480)/60<<":"<<(t-480)%60-1;
		}
	}
	if(t==480) cout<<0<<0<<":"<<0<<0;
	if(t<480){
		if((480-t)%60<10)cout<<0<<(480-t)/60<<":"<<0<<(480-t)%60-1;
		else cout<<0<<(480-t)/60<<":"<<(480-t)%60-1;
	}
	return 0;
}