How do I know which are the first characters before "/"? asp.net vb.net

Imports System.Text.RegularExpressions
// ...
Dim input As String = "Batch 235/689/45 pcs booked out by vladut moraru on 10/15/2015"

Dim regexString As String = "^Batch (?<Batch>[\d]{3}/[\d]{3})/(?<PCS>[\d]{2}).*$"

Dim regex As Regex = New Regex(regexString, RegexOptions.Compiled Or RegexOptions.CultureInvariant)

Dim m As Match = regex.Match(input)

Dim batch As String = m.Groups("Batch").Value
Dim pcs As String = m.Groups("PCS").Value

'' Yields batch = "235/689", pcs = "45"

Dim regExMatch2 As System.Text.RegularExpressions.Match
                           regExMatch = System.Text.RegularExpressions.Regex.Match(CheckIfBooked, "Batch (.+)/\d+ pcs", System.Text.RegularExpressions.RegexOptions.IgnoreCase)
                           regExMatch2 = System.Text.RegularExpressions.Regex.Match(CheckIfBooked, "Batch (.+)/(\d+) pcs", System.Text.RegularExpressions.RegexOptions.IgnoreCase)
                           If regExMatch.Success Then
                               batch = regExMatch.Groups(1).Value
                           End If