import java.util.*;

class MagicNumber
{
   private static double askWizard(long n)
   {
      Random r = new Random();
      double a = 0.0;
      double b = 0.0;
      double c = 0.0;

      for (long i = 0; i < n; i++) {
         a = (2.0*r.nextDouble()) - 1.0;
         b = (2.0*r.nextDouble()) - 1.0;
         if (((a*a) + (b*b)) <= 1.0) {
            c += 4.0/n;
         }
      }
      return c;
   }

   public static void main(String[] args)
   {
      long n = Long.parseLong(args[0]);

      System.out.println("The magic number is: " + askWizard(n));
   }
}