#Miller-Rabinの素数判定法
def Miller_Rabin_Primality_Test(N,Times=20):
    """Miller-Rabinによる整数Nの素数判定を行う.

    N:整数
    ※:Trueは正確にはProbably Trueである(Falseは確定False).
    """
    from random import randint as ri

    if N==2:
        return True

    if N==1 or N%2==0:
        return False

    q=N-1
    k=0
    while q&1==0:
        k+=1
        q>>=1

    for _ in range(Times):
        m=ri(2,N-1)
        y=pow(m,q,N)
        if y==1:
            continue

        flag=True
        for i in range(k):
            if (y+1)%N==0:
                flag=False
                break

            y*=y
            y%=N

        if flag:
            return False
    return True

#ポラード・ローアルゴリズムによって素因数を発見する
#参考元:https://judge.yosupo.jp/submission/6131
def Find_Factor_Rho(N):
    if N==1:
        return 1
    from math import gcd
    m=1<<(N.bit_length()//8+1)

    for c in range(1,99):
        f=lambda x:(x*x+c)%N
        y,r,q,g=2,1,1,1
        while g==1:
            x=y
            for i in range(r):
                y=f(y)
            k=0
            while k<r and g==1:
                for i in range(min(m, r - k)):
                    y=f(y)
                    q=q*abs(x - y)%N
                g=gcd(q,N)
                k+=m
            r <<=1

        if g<N:
            if Miller_Rabin_Primality_Test(g):
                return g
            elif Miller_Rabin_Primality_Test(N//g):
                return N//g
    return N

#ポラード・ローアルゴリズムによる素因数分解
#参考元:https://judge.yosupo.jp/submission/6131
def Pollard_Rho_Prime_Factorization(N):
    I=2
    res=[]
    while I*I<=N:
        if N%I==0:
            k=0
            while N%I==0:
                k+=1
                N//=I
            res.append([I,k])

        I+=1+(I%2)

        if I!=101 or N<2**20:
            continue

        while N>1:
            if Miller_Rabin_Primality_Test(N):
                res.append([N,1])
                N=1
            else:
                j=Find_Factor_Rho(N)
                k=0
                while N%j==0:
                    N//=j
                    k+=1
                res.append([j,k])
    if N>1:
        res.append([N,1])
    res.sort(key=lambda x:x[0])
    return res

def integer_product(T):
    a=1
    for t in T:
        a*=t
    return a

from itertools import product
def divisors(X):
    E=[[pow(p,k) for k in range(e+1)] for p,e in X]
    A=[integer_product(t) for t in product(*E)]
    A.sort()
    for a in A:
        yield a

def check(r):
    X=N
    p=X%r
    while X:
        if X%r!=p:
            return False
        X//=r
    return True
#================================================
N=int(input())
Y=Pollard_Rho_Prime_Factorization(N)
D=divisors(Y)
S=set()

X=N+1
for a in D:
    M=N//a

    Y=Pollard_Rho_Prime_Factorization(M-1)
    B=divisors(Y)

    for p in B:
        if p>=X:
            break

        if 2<=p and (p not in S):
            S.add(p)
            if check(p):
                X=p
print(X)