// Burton Rosenberg
// Wed Feb 4 1998
// SumOdd.java

import java.io.* ;

class SumOdd
{

   public static void main( String [] argv )
   throws IOException
   {
      BufferedReader stdin = new BufferedReader
         (new InputStreamReader(System.in)) ;

      System.out.print("N: " ) ;
      int i ;
      i = Integer.parseInt(stdin.readLine()) ;

      System.out.print( "The sum of the first " + i + " odd numbers is " ) ;
      System.out.println( sumOddNumbers( 2*i-1 ) + ".") ;

   }
   
   static int sumOddNumbers( int oddNumber ) 
   {
      // oddNumber should be an odd integer.
      if ( oddNumber<1 ) 
      {
         return 0 ;
      }
      else
      {
         return (oddNumber + sumOddNumbers( oddNumber-2 )) ;
      }
    
   }
}