Sub A()
Dim tablo, i&, x$
With Range("I19", Range("I" & Rows.Count).End(xlUp))
If .Row < 19 Or .Count = 1 Then Exit Sub
tablo = .Value
For i = 2 To UBound(tablo)
x = UCase(tablo(i, 1))
If x <> "" Then If Left(x, 1) <> "A" Then tablo(i, 1) = "A" & x
Next
.Value = tablo 'restitution
End With
End Sub