Given a number n. The task is to find the smallest number whose factorial contains at least n trailing zeroes.
n = 1
Explanation : 5! = 120 which has at
least 1 trailing 0.
n = 6
Explanation : 25! has at least
6 trailing 0.
Complete the function findNum() which takes an integer N as input parameters, and returns the answer.
Expected Time Complexity: O(log2 N * log5 N).
Expected Auxiliary Space: O(1).
1 <= n <= 104