Option Explicit
Private Sub Worksheet_Change(ByVal Target As Range)
Dim chn$, n&
With Target
If .CountLarge > 1 Then Exit Sub
If .Address <> "$B$3" Then Exit Sub
chn = .Value
If chn = "" Then [B5] = "": Exit Sub
End With
n = Application.CountIf([H19:L26], chn)
If n = 0 Then [B5] = "" Else [B5] = n
End Sub