Imports System

Public Module Module1

    Public Sub Main()

        dim inputMob as string="9048731111"

        dim inputLength as integer=inputMob.Length - 1

        dim CharArray=inputMob.ToCharArray()

        CharArray(inputLength)="X"

        CharArray(inputLength-1)="X" 

        Console.WriteLine("My Mobile Number      : {0}",inputMob)

        Console.WriteLine("Masked  Mobile Number : {0}",String.Join("",CharArray))

    End Sub

End Module