The square of the parabola y = - x, the focal coordinate is? I don't have any more,

The square of the parabola y = - x, the focal coordinate is? I don't have any more,

y²=-X=-2*(1/2)*x
So, P = 1 / 2
The focus coordinate is (- P / 2,0), that is (- 1 / 4,0)