Power of Four

Easy

Given an integer n, return true if it is a power of four (i.e., n == 4^x for some non-negative integer x).

Example 1

Input:  n = 16
Output: true

Example 2

Input:  n = 5
Output: false

Example 3

Input:  n = 1
Output: true

Constraints

• -2^31 <= n <= 2^31 - 1