Imports System
Imports System.Collections.Generic
Public Class Program
Public Shared Function findMininimumIndex(ByVal arr As Integer()) As Integer
Dim minIndex As Integer = -1
Dim st As ISet(Of Integer) = New HashSet(Of Integer)()
For i As Integer = arr.Length - 1 To 0 step -1
If st.Contains(arr(i)) Then
minIndex = i
Else
st.Add(arr(i))
End If
Next
Return minIndex
End Function
Public Shared Sub Main(ByVal args As String())
Dim arr As Integer() = New Integer() {3, 7, 8, 6, 9, 1, 8, 8, 6, 1, 1, 8}
Console.Write(findMininimumIndex(arr))
End Sub
End Class