#include<fstream.h>
main()
{long p,n=0;
 ifstream i("fact.in");
 ofstream o("fact.out");
 i>>p;

 while(p>0)
  {n=n+25;
   p=p-5;
  }
 while(p<0)
  {n=n-5;
   p++;
  }
 o<<n<<'\n';
 i.close();
 o.close();
 return 0;
}