If IsError(Application.Match(Range("A1"), Range("A2:A20"),  0 )) _
      Then Exit Sub

Dim myArr()
i = Cells(Rows.Count,  1 ).End(xlUp).Row
For x =  2  To i
    myArr(x -  2 ) = Range("A" & x)
Next x

i = Cells(Rows.Count,  1 ).End(xlUp).Row
For x =  2  To i
    If Cells(x,  1 ).Value <> Cells( 1 ,  1 ).Value Then Exit Sub
Next x

    With ThisWorkbook.Worksheets("Otchet")
        i = .Cells(Rows.Count,  1 ).End(xlUp).Row
        a = .Range("A2").Value
        b = Val(a) +  1 
        Do
            If b >  0  And b <  10  Then c = "0" & Val(b) Else c = CStr((b))
            If Not .Range("A3:A" & i).Find(c) Is Nothing Then Exit Sub
                
            If b =  15  Then b =  0 
            b = Val(b) +  1 
        Loop While Val(a) <> b
    End With

Function X( _
  rng1 As Range, _
  rng2 As Range) As Boolean
  
    Dim avarData() As Variant
    Dim avarItem As Variant
    
    avarData = rng2.Value
    
    For Each avarItem In avarData
        If avarItem <> rng1.Value Then
            X = True
            Exit For
        End If
    Next
End Function

Sub Y()
    If X(Range("A1"), Range("A2:A20")) Then Exit Sub
    
    MsgBox "Test"
End Sub

If avarItem <> rng1.Value Then
            X = True
            Exit For
        End If

 If rng1.Value <> WorksheetFunction.And(rng2.Value) Then Exit Sub

 If rng1.Value <> Array(WorksheetFunction.And(rng2.Value)) Then Exit Sub

On Error Resume Next
Set r1 = ActiveSheet.Columns("A").ColumnDifferences(Comparison:=ActiveSheet.Range("A1"))
If Error =  0  Then r1.Select Else Exit Sub

Set r1 = ActiveSheet.Columns("A").ColumnDifferences(Comparison:=ActiveSheet.Range("A2"))
If r1.Count >  1   Then Exit Sub

    Dim r1 As Range
    i = Cells(Rows.Count,  1 ).End(xlUp).Row
    On Error Resume Next
    Set r1 = Range("A3:A" & i).ColumnDifferences(Comparison:=Range("A2"))
    If Err.Number <>  0  Then Exit Sub