# -*- coding: utf-8 -*- 
import sys,math
def isprime(q):
  if q==2: return True
  if q<2 or q&1==0: return False
  return pow(2,q-1,q)==1
  
a=[0,0,0,0,3,0,5,0,7,7,7,0,11,0,13,7,7,0,8,0,19,19,7,0,23,25]
x=input()
if x<=25:
  print a[x]
elif (x-1)%8==0 and isprime(x-8):
  print 14
else:
  print 8