#include <bits/stdc++.h>
using namespace std;
typedef long long ll;

int main() {
    ll n;
    cin>>n;
    for (ll i=3;i*i<=n;i++) {
        if (n%i==0) {
            cout<<i<<endl;
            return 0;
        }
    }
    if (n%2==0&&n/2>2) cout<<n/2<<endl;
    else cout<<n<<endl;
    return 0;
}