#include <bits/stdc++.h>
#include <math.h>
using namespace std;
int main()
{
	double s,v;
	int h=7,m=50,t;
	int H,M;
	cin>>s>>v;
	t=ceil(1.0*s/v);
	H=t/60; M=t%60;
	if(H>h) h+=24;
	h-=H; m-=M;
	if(m>=60) {m%=60; h++;}
	if(h<10) cout<<0;
	cout<<h<<':';
	if(m<10) cout<<0;
	cout<<m;
	return 0;
}