Your friends collect butterflies and stamps, but you collect numbers. Your collection of prime numbers is the finest in three counties, and your collection of transcendental numbers has been featured on national talkshows. Lately you've decided to start collecting powers, that is, numbers that can be written in the form MK, where M and K are positive integers with K > 1. However, you're wondering how big a box you'll need to hold them all. Given a number N, represented as a String, determine how many powers lie between 1 and N, inclusive. Return the number of powers as a String with no leading zeros.