# -*- coding: utf-8 -*-

N = input()

i = 3
found = False
ans = 1e9

while i * i <= N:
    if N % i == 0:
        found = True
        ans = min(ans, i)
        break
    i += 1

if found == False and N % 2 == 0 and N != 4:
    i = N / 2
    found = True
    
print i if found else N