import math

n = int(input())

def find_min_k(n):
    if n % 2 == 0:
        min_k = None
        if n % 4 == 0:
            min_k = 4
        sqrt_n = int(math.isqrt(n))
        for i in range(3, sqrt_n + 1, 2):
            if n % i == 0:
                if min_k is None or i < min_k:
                    min_k = i
                counterpart = n // i
                if counterpart >= 3 and (min_k is None or counterpart < min_k):
                    min_k = counterpart
        if min_k is not None:
            return min_k
        else:
            return 4 if n % 4 == 0 else n // 2
    else:
        min_k = None
        sqrt_n = int(math.isqrt(n))
        for i in range(3, sqrt_n + 1, 2):
            if n % i == 0:
                if min_k is None or i < min_k:
                    min_k = i
                counterpart = n // i
                if counterpart >= 3 and (min_k is None or counterpart < min_k):
                    min_k = counterpart
        return min_k if min_k is not None else n

print(find_min_k(n))