#coding: UTF-8

import sys
from operator import itemgetter
import re
import itertools
import math

N = input()

while (N%2==0):
	N /= 2
	
flg = True
for i in range(3,long(math.sqrt(N)+1)):
	if (N%i==0):
		print i
		flg = False
		break

if (flg) :
	print N