I have a datagridview in which I have three columns 

1- int value in datagridviewtextbox

2- int value in datagridviewtextbox

3- checkbox

I want when i check any checkbox its (row) corresponding 1st column value should be added in global variable '`TOTAL`' (which is pre defined)

```
private void dataGridView1_CellValueChanged(object sender, DataGridViewCellEventArgs e)
    {
        label16.Text = 0.ToString();
        label17.Text = 0.ToString();
        label18.Text = 0.ToString();
        foreach (DataGridViewRow drow in dataGridView1.Rows)
        {
            if (Convert.ToBoolean(drow.Cells[4].Value) == true)
            {
                label16.Text = (Convert.ToDecimal(label16.Text) + Convert.ToDecimal(drow.Cells[1].Value)).ToString();
                label17.Text = (Convert.ToDecimal(label17.Text) + Convert.ToDecimal(label12.Text)).ToString();
                label18.Text = (Convert.ToDecimal(label18.Text) + Convert.ToDecimal(drow.Cells[2].Value)).ToString();
            }
        }
    }

```

it works when current row changes but i want when i click the checkbox immediately
it update label16,17,18