# -*- coding: utf-8 -*-
import random

N = int(input())
    
def isPrime(n, k = 50):
    d = (n - 1) >> 1
    while d & 1 == 0:
        d >>= 1
    for i in range(k):
        a = random.randint(1, n - 1)
        t = d
        y = pow(a, t, n)
        while t != n - 1 and y != 1 and y != n - 1: 
            y = pow(y, 2, n)
            t <<= 1
        if y != n - 1 and t & 1 == 0:
            return False
    return True

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, 23]

if N < 26:
    print A[N]
else:
    if N % 8 != 1:
        print 8
    else:
        print 14 if isPrime(N - 8) else 8