Question about sum a column in dataGrip view

Dim Profit As Integer = 0
        Dim counter As Integer
        For counter = 0 To (DataGridView1.Rows.Count - 1)
            If Not DataGridView1.Rows(counter).Cells("Amount").Value Is Nothing Then
                If Not DataGridView1.Rows(counter).Cells("Amount").Value.ToString().Length = 0 Then
                    Profit += Integer.Parse(DataGridView1.Rows(counter).Cells("Amount").Value.ToString())
                End If
            End If
        Next
        TextBox6.Text = Profit