$30\mathrm{.}5\mathrm{.}1$: Write a recursive method to compute a power of two.

$597714\mathrm{.}2988516.$qx$3$zqy$7$

In order to compute a power of two, you can take the next$-$lower power and double it$.$ For example, if you want to compute $211$ and you know that $210=1024,$ then $211=21024=2048.$ Write a recursive method

public static int pow$2($int n$)$

where n is the exponent, that is based on this observation. If the exponent is negative, return $-1.$