#約数全部
def Divisors(N):
    N=abs(N)
    L,U=[],[]
    k=1
    while k*k <=N:
        if N%k== 0:
            L.append(k)
            if k!=N//k:
                U.append(N//k)
        k+=1
    return L+U[::-1]
#================================================
N=int(input())
R=Divisors(N)

for a in R:
    if a>=3:
        print(a)
        exit()