#include <iostream>
#include <cmath>
using namespace std;
float s,v;
int main(){
	
	cin >> s >> v;
	int time = ceil(s/v);
	
	int number = 470;
	int losetime;
	losetime = number - time;
	
	if(losetime > 0){
		cout << "0";
		cout << losetime / 60<<":";
		if(losetime % 60 != 0){
				cout << losetime % 60;
		}else{
			cout <<"00";
		}
		return 0;
	}else if(losetime < 0){
		losetime = 1440 + losetime; 
		if(losetime / 60 < 10){
			cout << "0";
		}
		if(losetime > 480){
			cout << losetime / 60 << ":";
			if(losetime % 60 != 0){
				cout << losetime % 60; 
			}else{
				cout << "00";
			}
		}else{
			cout << "8:00";
			
		}
		return 0;
	}else if(losetime == 0){
		cout << "00:00";
		return 0;
	}
	return 0;
}