try
{
double y1, y2, p1, p2, ort;
y1 = Convert.ToDouble(textBox2.Text);
y2 = Convert.ToDouble(textBox3.Text);
p1 = Convert.ToDouble(textBox4.Text);
p2 = Convert.ToDouble(textBox5.Text);
ort = (y1 + y2 + p1 + p2) / 4;
txtEditor.Text = ort.ToString();
}
catch
{...