#include<bits/stdc++.h>
using namespace std;
int main()
{
	int t,timeh,timem;
	double s,v;
	cin>>s>>v;
	t=ceil(s/v);
	t=470-t;
	while(t<0) 
	{
	t+=1440;
	}
	timeh=t/60;
	timem=t%60;
	if(timem>=10)
	{
		cout<<timeh<<":"<<timem;
	}
	else
	{
		cout<<timeh<<":0"<<timem;
	}
	return 0;
}