#include<bits/stdc++.h>
using namespace std;
int summ,t;
double a,b;
int main(){
	cin>>a>>b;
	summ = 10;
	summ +=  ceil( a/b );
	t=480;
	t-=summ;
	int mi = t%60;
	t/=60;
	if (t < 9) cout<<"0";
	cout<<t<<":";
	if (mi < 9) cout<<"0";
	cout<<mi;
	return 0;
}