#include <iostream>
 using namespace std;
 int main(){
	
  
  
int s,v;
cin >> s >> v;
double time;
	
time = (double)s /(double)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";
	}
}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";
	}
}else if(losetime == 0){
	cout << "00:00";
}
return 0;
}