#include <cstdio>
#include <cstring>
#include <iostream>
#include <string>
#include <cmath>
#include <bitset>
#include <vector>
#include <map>
#include <set>
#include <queue>
#include <deque>
#include <algorithm>
#include <complex>
#include <unordered_map>
#include <unordered_set>
#include <random>
#include <cassert>
#include <fstream>
#include <utility>
#include <functional>
#include <time.h>
#include <stack>
#include <array>
#include <list>
#define popcount __builtin_popcount
using namespace std;
typedef long long ll;
typedef pair<int, int> P;

int main()
{
    ll n; cin>>n;
    if(n==1){
        cout<<2<<endl;
        return 0;
    }else if(n==2){
        cout<<3<<endl;
        return 0;
    }
    for(ll i=2; i*i<=n; i++){
        ll d[50];
        int k=0;
        ll x=n;
        while(x){
            d[k++]=x%i;
            x/=i;
        }
        bool dame=0;
        for(int j=0; j<k-1; j++){
            if(d[j]!=d[j+1]){
                dame=1; break;
            }
        }
        if(!dame){
            cout<<i<<endl;
            return 0;
        }
    }
    vector<ll> v;
    for(ll i=1; i*i<=n; i++){
        if(n%i==0){
            v.push_back(i);
            if(i*i<n) v.push_back(n/i);
        }
    }
    sort(v.begin(), v.end());
    for(auto x:v){
        ll p=x-1;
        if(p<2 || p*p<=n) continue;
        cout<<p<<endl;
        return 0;
    }
    return 0;
}