#include "bits/stdc++.h"
using namespace std;
#define FOR(i,j,k) for(int (i)=(j);(i)<(int)(k);++(i))
#define rep(i,j) FOR(i,0,j)
#define each(x,y) for(auto &(x):(y))
#define mp make_pair
#define all(x) (x).begin(),(x).end()
#define debug(x) cout<<#x<<": "<<(x)<<endl
#define smax(x,y) (x)=max((x),(y))
#define smin(x,y) (x)=min((x),(y))
#define MEM(x,y) memset((x),(y),sizeof (x))
#define sz(x) (int)(x).size()
typedef long long ll;
typedef pair<int, int> pii;
typedef vector<int> vi;
typedef vector<ll> vll;

vector<long long> divisors(long long n){
    vector<long long> res;
    for(long long i=1; i*i<=n; ++i){
        if(n%i==0){
            res.push_back(i);
            long long j = n/i;
            if(j!=i)res.push_back(j);
        }
    }
    return res;
}

int main(){
    ll n; cin >> n;
    auto ds = divisors(n);
    sort(all(ds));
    each(d, ds){
        if(d >= 3){
            cout << d << endl;
            return 0;
        }
    }
}