from collections import deque
import math
import random

prime=[1]*1000
prime[0]=0
prime[1]=0
for i in range(2,1000):
    if prime[i]==0:
        continue
    j=i+i
    while j<1000:
        prime[j]=0
        j+=i

N=int(input())
dx=[1,0,-1,0]
dy=[0,1,0,-1]
def solvenaive(W):#幅Wに対して愚直に
    H=(N+W-1)//W
    que=deque()
    que.append(0)
    dist=[0]*N
    dist[0]=1
    while que:
        now=que.popleft()
        x=now//W
        y=now%W
        for i in range(4):
            nx=x+dx[i]
            ny=y+dy[i]
            if(nx<0 or ny<0 or nx>=H or ny>=W):
                continue
            if nx*W+ny>N-1:
                continue
            if prime[nx*W+ny+1]:
                continue
            if dist[nx*W+ny]:
                continue
            dist[nx*W+ny]=1
            que.append(nx*W+ny)
    return dist[N-1]


if N<=500:
    for i in range(1,N+1):
        if solvenaive(i):
            print(i)
            exit()


def is_prime(n):
    if n == 1: return False
    if n == 2: return True

    for k in range(100):
        a = random.randint(2, n - 1)

        if gcd(n, a) != 1:
            return False

        if pow(a, n - 1, n) != 1:
            return False

    return True

def gcd(a, b):
    while b > 0:
        a, b = b, a % b
    return a

if not N%8==1:
    print(8)
else:
    if not is_prime(N-8):
        print(8)
    else:
        print(14)