using System;

public class Program

{

    public static void Main()

    {

        int Sum = 0, Br = 0;

do { int A = int.Parse ( Console.ReadLine ( ) ) ;

if ( A % 2 != 0 ) { Sum = Sum + A ; Br++ ; } } while ( A != 0 );

Console.WriteLine ( ( float ) Sum / Br);

​

​

    }

}