How to display sum of cells in C# datagridview ?

private void dataGridView1_CurrentCellChanged(object sender, EventArgs e)
{
for(int i=0;i
{
int c1 = Convert.ToInt32(dataGridView1.Rows[i].Cells[1].Value);
int c2 = Convert.ToInt32(dataGridView1.Rows[i].Cells[2].Value);
int c3 = Convert.ToInt32(dataGridView1.Rows[i].Cells[3].Value);
int c4 = Convert.ToInt32(dataGridView1.Rows[i].Cells[4].Value);
dataGridView1.Rows[i].Cells[5].Value = (c1+c2+c3+c4);
}
}
//Horizontal sum can be done in this way