from sys import stdin, stdout
from decimal import Decimal as d

def dec_range(x,y):
  x= d(x)
  y= d(y)
  while x < y:
    yield x
    x= x+1

def f(n):
  n= d(n)
  for y in dec_range(d(3),n):
    if n%y == d(0): return y
  return n

n= stdin.readline()
print f(n)