Imports System

   Class Moyenne
      Overloads Shared Sub Main( ByVal args() As String )
        
         Try 
            Dim n As Integer = Val( Console.ReadLine( ) )
            Dim somme As Integer = 0
            Dim cpt As Integer = 0

	    While n > 0
	      somme = somme + n
              n = Val( Console.ReadLine( ) )
	      cpt = cpt + 1
	    End While

	    Console.WriteLine( "{0:f2}", somme / cpt )

         Catch ex As Exception
            Console.WriteLine( ex.Message ) 
      End Try

      End Sub
   End Class