Enter x if the graph of the given equation is symmetric with respect to the $x$-axis, y if it is symmetric with respect to the $y$ axis, o (lower case O) if it is symmetric with respect to the origin, and n (for None) if it has none of these three symmetries.

$y=x+1$
$y=x^3$
$y=x^2$
$x=y^2$