Excel VBA Macro To Concatenate First Column of Each Sheet In Main Sheet

Excel VBA Macro To Concatenate First Column of Each Sheet In Main Sheet
Sub ConcateColumns()
Dim X As Integer
Dim Y As Integer
Dim Z As Integer
Dim W As Worksheet
Dim A As Integer

A = 1 'Variable for Column Increment In Main Sheet

For Each W In Worksheets

If W.Name <> Sheets("MAIN").Name Then
W.Activate

For X = 1 To 100

If Cells(X, 1) <> "" Then
Z = Z + 1 'Row Increment Variable
Sheets("MAIN").Cells(Z, A) = W.Cells(X, 1)
End If

Next X
A = A + 1 'Variable for Column Increment In Main Sheet

End If
Z = 0

Next W
End Sub

Note:
First Column of Each Sheet Comes Side By Side(Concatenation Mode) in Main Sheet.

Thanks,Tamatam