An ugly number is a positive integer whose prime factors are limited to 2, 3, and 5.
Given an integer n, return the nth ugly number.
Note that 1 is typically treated as an ugly number.
Example 1:
Input: n = 10
Output: 12
Explanation: The first 10 ugly numbers are [1, 2, 3, 4, 5, 6, 8, 9, 10, 12]. The 10th ugly number is 12.
Example 2:
Input: n = 1
Output: 1
Explanation: 1 is the first ugly number by convention.
Example 3:
Input: n = 11
Output: 15
Explanation: The first 11 ugly numbers are [1, 2, 3, 4, 5, 6, 8, 9, 10, 12, 15]. The 11th ugly number is 15.
1 <= n <= 1690