how to get the serial number for datagridview rows

Hi ,

This code does not works for merged rows.I want to get the Serial number for Merged rows. For example there 3 colums C1(seria no),C2,C3. For one value of C2 there is multiple values of C3. Therefore I have merged C2 for same values. But I am not able to get serial number for C2.

I am using below code for Merging the C2 for same values:

protected void GrdReportingDetails_PreRender(object sender, EventArgs e)
{
GridDecorator.MergeRows(GrdReportingDetails);
}
}


public class GridDecorator
{
public static void MergeRows(GridView gridView)
{
for (int rowIndex = gridView.Rows.Count - 2; rowIndex >= 0; rowIndex--)
{
GridViewRow row = gridView.Rows[rowIndex];
GridViewRow previousRow = gridView.Rows[rowIndex + 1];

for (int i = 1; i < row.Cells.Count; i++)
{
if (row.Cells[i].Text == previousRow.Cells[i].Text)
{
row.Cells[i].RowSpan = previousRow.Cells[i].RowSpan < 2 ? 2 :
previousRow.Cells[i].RowSpan + 1;
previousRow.Cells[i].Visible = false;
}
}
}
}
}