Sub copy()
    Dim FilesToOpen
    Dim x As Integer
    
    Application.ScreenUpdating = False
    
    FilesToOpen = Application.GetOpenFilename(fileFilter:="all files (*.*), *.*", MultiSelect:=True, Title:="Files to merge")
    
    If TypeName(FilesToOpen) = "Boolean" Then
        MsgBox "не выбрано ни одного файла!"
        Exit Sub
    End If
    
    x = 1
    While x <= UBound(FilesToOpen)
        Set importWB = Workbooks.Open(Filename:=FilesToOpen(x))
        Sheets().Copy after:=ThisWorkbook.Sheets(ThisWorkbook.Sheets.Count)
        importWB.Close savechanges:=False
        x = x + 1
        
    Wend
    
    Application.ScreenUpdating = True
        
End Sub