Public Function extrait(ch As String, n As Integer) As String
Dim k As Long, flt As String, titi
flt = String(n, "#")
titi = Split(StrConv(ch, vbUnicode), Chr(0))
For i = 0 To UBound(titi) - 1
If Not IsNumeric(titi(i)) Then titi(i) = Chr(1)
Next
titi = Split(Join(titi, ""), Chr(1))
For k = 1 To UBound(titi)
If titi(k) Like flt Then
extrait = extrait & "-" & titi(k)
End If
Next
extrait = Mid(extrait, 2)
End Function