/*
TASK:crossing
LANG:C++
*/
# include <iostream>
using namespace std;
int main ()

{   double w,s,a,b,t1,t,t2,t3;
     int  l,m,n,p;
    cin >>w>>s>>a>>b;
    if (a>b )  cout << "nekorekten vhod" <<endl;
    if (b>=20) cout << "nekorekten vhod" <<endl;
    if (w>s)   cout <<"nekorekten vhod"<<endl;
    if (s>40)  cout <<"nekorekten vhod"<<endl;
    t1=(w/2)/a;
    t2=s/b;
    t3=(w/2)/a;
    t=t1+t2+t3;
   p=t;
   if (p==0)
   {
   n=1;}
   else n=p;
   l=15;
   m=20;
  


   cout <<n<<":"<<l<<":"<<m<<endl;





   return 0;

}
