#include<bits/stdc++.h>
using namespace std;
#define int long long
#define REP(i,m,n) for(int i=(m);i<(n);i++)
#define rep(i,n) REP(i,0,n)
#define pb push_back
#define all(a) a.begin(),a.end()
#define rall(c) (c).rbegin(),(c).rend()
#define mp make_pair
#define endl '\n'
#define vec vector<ll>
#define mat vector<vector<ll> >
#define fi first
#define se second
typedef long long ll;
typedef unsigned long long ull;
typedef pair<ll,ll> pll;
typedef long double ld;
typedef complex<double> Complex;
const ll INF=1e9+7;
const ll inf=INF*INF;
const int mod=1e9+7;
const ll MAX=100010;
const double PI=acos(-1.0);

signed main(){
    ll n;cin>>n;
    if(n==2){
        cout<<3<<endl;
        return 0;
    }else if(n==1){
        cout<<2<<endl;
        return 0;
    }
    map<ll,ll>ma;
    ll ans=n-1;
    REP(i,2,sqrt(n+1)){
        ll now=1;
        ll sum=0;
        while(sum<=n){
            sum+=now;
            if(n%sum==0&&i>n/sum){
                if(ma[sum]==0){
                    ma[sum]=i;
                }
            }
            now*=i;
        }
    }
    vector<ll>p(0);
    REP(i,2,sqrt(n+1)){
        if(n%i==0){
            p.pb(i);
            p.pb(n/i);
        }
    }
    p.pb(n);
    rep(i,p.size()){
        if(ma[p[i]]!=0){
            ans=min(ans,ma[p[i]]);
        }
        if(n/p[i]<p[i]-1)ans=min(ans,p[i]-1);
    }

    cout<<ans<<endl;
}