import sys

# sys.setrecursionlimit(200005)
int1 = lambda x: int(x)-1
pDB = lambda *x: print(*x, end="\n", file=sys.stderr)
p2D = lambda x: print(*x, sep="\n", end="\n\n", file=sys.stderr)
def II(): return int(sys.stdin.readline())
def LI(): return list(map(int, sys.stdin.readline().split()))
def LLI(rows_number): return [LI() for _ in range(rows_number)]
def LI1(): return list(map(int1, sys.stdin.readline().split()))
def LLI1(rows_number): return [LI1() for _ in range(rows_number)]
def SI(): return sys.stdin.readline().rstrip()

dij = [(0, 1), (-1, 0), (0, -1), (1, 0)]
# dij = [(0, 1), (-1, 0), (0, -1), (1, 0), (1, 1), (1, -1), (-1, 1), (-1, -1)]
inf = (1 << 63)-1
# inf = (1 << 31)-1
# md = 10**9+7
md = 998244353

from random import randrange

def is_prime(n):
    # K...信頼度
    K = 20
    if n == 2: return True
    if n == 1 or n & 1 == 0: return False
    d = (n-1) >> 1
    while d & 1 == 0: d >>= 1
    for k in range(K):
        a = randrange(1, n)
        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

primes = set(
    [2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89, 97, 101, 103, 107,
     109, 113, 127, 131, 137, 139, 149, 151, 157, 163, 167, 173, 179, 181, 191, 193, 197, 199, 211, 223, 227, 229,
     233, 239, 241, 251, 257, 263, 269, 271, 277, 281, 283, 293, 307, 311, 313, 317, 331, 337, 347, 349, 353, 359,
     367, 373, 379, 383, 389, 397, 401, 409, 419, 421, 431, 433, 439, 443, 449, 457, 461, 463, 467, 479, 487, 491,
     499])

def ok(w):
    def push(ij):
        if fin[ij]: return
        fin[ij] = 1
        st.append(ij)

    fin = [0]*n
    for p in primes:
        if p-1 >= n: break
        fin[p-1] = 1
    fin[0] = 1
    st = [0]
    while st:
        ij = st.pop()
        if ij == n-1: return True
        i, j = divmod(ij, w)
        if i: push(ij-w)
        if j: push(ij-1)
        if ij+w < n: push(ij+w)
        if j+1 < w: push(ij+1)
    return False

def ok1(w):
    def push(ij):
        if ij in fin: return
        fin.add(ij)
        if ij+1 in primes: return
        st.append(ij)

    fin = set()
    st = [0]
    while st:
        ij = st.pop()
        i, j = divmod(ij, w)
        if i > d or j > d:
            return True
        if i: push(ij-w)
        if j: push(ij-1)
        if ij+w < n: push(ij+w)
        if j+1 < w: push(ij+1)
    return False

def ok2(w):
    def push(ij):
        if ij in fin: return
        fin.add(ij)
        if is_prime(ij+1): return
        st.append(ij)

    fin = set()
    gi, gj = divmod(n-1, w)
    st = [n-1]
    while st:
        ij = st.pop()
        i, j = divmod(ij, w)
        if abs(i-gi) > d or abs(j-gj) > d:
            return True
        if i: push(ij-w)
        if j: push(ij-1)
        if ij+w < n: push(ij+w)
        if j+1 < w and ij+1 < n: push(ij+1)
    return False

d = 9
n = II()
if n < 500:
    for w in range(3, n+1):
        if ok(w):
            print(w)
            exit()
else:
    for w in range(8, 1000):
        if ok1(w) and ok2(w):
            print(w)
            exit()