#include<bits/stdc++.h>
using namespace std;
int main()
{
	int p,q,m,n;
	double s,v,t;
	cin>>s>>v;
	t=ceil(s/v+10);
	p=32*60;
	p=p-t;
    if(p>=24*60) p-=24*60;
    m=p/60;
    n=p%60;
    if(m>10)
    {
      if(n>10) cout<<m<<":"<<n;
	  else cout<<m<<":0"<<n; 	
	}
	else
	{
	   if(n>10) cout<<"0"<<m<<":"<<n;
	   else cout<<"0"<<m<<"0:"<<n;
	}
return 0;
}