N = int(input())

def make_divisors(n):
    lower_divisors , upper_divisors = [], []
    i = 1
    while i*i <= n:
        if n % i == 0:
            lower_divisors.append(i)
            if i != n // i:
                upper_divisors.append(n//i)
        i += 1
    return lower_divisors + upper_divisors[::-1]

p = make_divisors(N)
p.sort()
for v in p:
    if v > 2 and N % v == 0:
        ans = v
        break
else:
    if N % 2 == 0:
        ans = N // 2
    else:
        ans = N
print(ans)