#include <bits/stdc++.h>
//#include <chrono>
//#pragma GCC optimize("O3")
using namespace std;
#define reps(i,s,n) for(int i = s; i < n; i++)
#define rep(i,n) reps(i,0,n)
#define Rreps(i,n,e) for(int i = n - 1; i >= e; --i)
#define Rrep(i,n) Rreps(i,n,0)
#define ALL(a) a.begin(), a.end()

using ll = long long;
using vec = vector<ll>;
using mat = vector<vec>;

ll N,M,H,W,Q,K,A,B;
string S;
using P = pair<ll, ll>;
const ll INF = (1LL<<60);

template<class T> bool chmin(T &a, const T &b){
    if(a > b) {a = b; return true;}
    else return false;
}
template<class T> bool chmax(T &a, const T &b){
    if(a < b) {a = b; return true;}
    else return false;
}
template<class T> void print_vector(std::vector<T> v,bool endline = true){
    if(!v.empty()){
        for(std::size_t i{}; i<v.size()-1; ++i) std::cout<<v[i]<<" ";
        std::cout<<v.back();
    }
    if(endline) std::cout<<std::endl;
}

int main(){
    cin.tie(nullptr);
    ios::sync_with_stdio(false);
    cin>>N;
    for(ll p = 2; p * p <= N; ++p){
        ll r = N%p, n = N;
        while(n && n%p == r) n /= p;
        if(n==0){
            cout<<p<<endl;
            return 0;
        }
    }
    ll res = N - 1;
    for(ll r = 2, n = N - 2; n / r > r; ++r, --n){
        if(n%r == 0) res = n / r;
    }
    cout<<res<<endl;
}