import math

N=int(input())

#素数の表の作成
n_sqrt = math.ceil(math.sqrt(N))
isPrime = [True for i in range(n_sqrt)]
primes = []

for i in range(4,n_sqrt,2):
    isPrime[i]=False

for i in range(3,n_sqrt,2):
    if isPrime[i]==True:
        primes.append(i)
        for j in range(i+i,n_sqrt,i):
            isPrime[j]=False

for i in primes:
    if N%i==0:
        print(i)
        exit()
print(N)