Imports System

Public Module Module1

    Public Sub Main()

        Dim x As Integer

        Dim count As Integer = 0

        Dim check As Boolean

        Do

            x = Console.ReadLine()

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            If x < 0 Then

                Console.WriteLine("please input again")

                check = False

            Else

                check = True

            End If

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        Loop Until check = True

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        Do

            count = count + 1

            For i = 1 To (x - count)

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                Console.Write("  ")

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            Next

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            For i = 1 To count

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                Console.Write("x")

                Console.Write(" ")

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            Next

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            Console.WriteLine(" ")

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        Loop Until count = x

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        Console.ReadLine()

    End Sub

End Module