Description

Original source: NOIP 2012 Popularization Group

Given a positive integer $n$ which is the product of two distinct prime numbers, determine the larger of the two primes.

Input Format

The input consists of a single line containing a positive integer $n$.

Output Format

The output should be a single line containing a positive integer $p$, which is the larger of the two primes.

Sample 1

21

7

Constraints and Hints

For $30\%$ of the data, $n\le 1000$;
For all data, $6\le n\le 2\times 10^9$.