#!/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