n = int(input())
nn = 10**6
num = [3,4]
table = [True] * (nn + 1)

for i in range(2, nn + 1):
    if not table[i]:
        continue
    k = i + i
    while k < nn + 1:
        table[k] = False
        k += i

    if i == 2 or i == 3 or i == 4:
        continue
    num.append(i)

flag = 0
for i in num:
    if n % i == 0:
        print(i)
        exit()

if n % 2 == 0:
    print(n//2)
    exit()
print(n)