import collections

def prime_factorize(n):
    a = []
    while n % 2 == 0:
        a.append(2)
        n //= 2
    f = 3
    while f * f <= n:
        if n % f == 0:
            a.append(f)
            n //= f
        else:
            f += 2
    if n != 1:
        a.append(n)
    return a

def n_fact(N):
    c = collections.Counter(prime_factorize(N))
    return c

N = int(input())
ans = 10 ** 13
dic = n_fact(N)
for k,v in dic.items():
    if k == 2:
        if v > 1:
            ans = min(ans,4)
    else:
        ans = min(ans,k)
print(ans)