how to found a unique record in datagridview and how find the location index of that item in datagridview

for (int i = 0; i <= dataGridView1.CurrentCell.RowIndex; i++)
           {
               al.Add(dataGridView1[0, i].Value.ToString());

               foreach (string[] a1 in al)
               {
                   if (comboBox2.SelectedValue == a1)
                   {

                       int tota = (int)dataGridView1[5, i].Value;

                       TotalRupees += tota;

                   }
                   else
                   {

                   }
               }
           }