Smart number is a number which has at least three distinct prime factors. Given a number n, find the n’th smart number.

Example 1:
Input:
n = 1
Output:
30
Explanation:
30 is the first number which has 3 prime
factors. So, it's the first Smart Number.
Example 2:
Input:
n = 2
Output:
42
Explanation:
42 = 237, 42 is the second number which
has 3 prime factors or more. So, it's the
second Smart Number.

Your Task:
You don't need to read input or print anything. Your task is to complete the function nthSmartNum() which takes an Integer n as input and returns the n'th Smart Number.

Expected Time Complexity: O(nloglogn)
Expected Auxiliary Space: O(n)

Constraints:
1 <= n <= 10^{5}

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