N = int(input())

def divisors(N):
    res = []
    for i in range(1, int(N ** 0.5) + 1):
        if N % i == 0:
            res.append(i)
            if i * i != N:
                res.append(N // i)
    res.sort()
    return res

div = divisors(N)
for d in div:
    if d > 2:
        print(d)
        exit()