#!/usr/bin/python
from collections import defaultdict

def divisors(n):
    sq = int(n ** .5)
    res = ((i, n/i) for i in xrange(1, sq+1) if n%i==0)
    from itertools import chain
    flatten = chain.from_iterable
    return flatten(res)

n = int(raw_input())
arr = sorted(filter(lambda x:x>2, divisors(n)))
res = arr[0]
print res