#include <bits/stdc++.h>

using namespace std;

#define all(hoge) (hoge).begin(), (hoge).end()
#define en '\n'
using ll = long long;
using ull = unsigned long long;
#define rep(i, m, n) for(ll i = (ll)(m); i < (ll)(n); ++i)
#define rep2(i, m, n) for(ll i = (ll)(n)-1; i >= (ll)(m); --i)
#define REP(i, n) rep(i, 0, n)
#define REP2(i, n) rep2(i, 0, n)
template<class T> using vec = vector<T>;
template<class T> using vvec = vector<vec<T>>;
typedef pair<ll, ll> P;
using tp = tuple<ll, ll, ll>;

constexpr long long INF = 1LL << 60;
constexpr int INF_INT = 1 << 25;
constexpr long long MOD = (ll) 1e9 + 7;
//constexpr long long MOD = 998244353LL;
using ld = long double;
static const ld pi = 3.141592653589793L;

using Array = vector<ll>;
using Matrix = vector<Array>;

/*
#pragma GCC target("avx2")
#pragma GCC optimize("O3")
#pragma GCC optimize("unroll-loops")
*/

template<class T>
inline bool chmin(T &a, T b) {
    if (a > b) {
        a = b;
        return true;
    }
    return false;
}

template<class T>
inline bool chmax(T &a, T b) {
    if (a < b) {
        a = b;
        return true;
    }
    return false;
}

void divisor(ll n, vector<ll>& ret) {
 for (ll i = 1; i * i <= n; i++) {
  if (n % i == 0) {
   ret.push_back(i);
   if (i * i != n) ret.push_back(n / i);
  }
 }
 sort(ret.begin(), ret.end());
}

void solve() {
    ll n;
    cin >> n;
    //３桁以上
    for(ll i=2;i*i<n;i++){
        ll tmp=n;
        ll x=tmp%i;
        tmp/=i;
        while(tmp%i==x){
            tmp/=i;
        }
        if(tmp) continue;
        cout<<i<<en;
        return;
    }
    //2桁の場合
    vec<ll> ret;
    divisor(n,ret);
    for(auto i:ret){
        if(i<3)continue;
        ll t = i-1;
        if(n/i >= t) continue;
        cout<<t<<en;
        return;
    }
    cout<<n+1<<en;
}

int main() {
    ios::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);
    /*
    ll t;
    cin >> t;
    REP(i, t - 1) {
        solve();
    }*/

    solve();

    return 0;
}