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

int main(){
    cin.tie(nullptr);
    ios::sync_with_stdio(false);

    long long n;
    cin >> n;

    for(long long i = 3; i <= (long long)sqrt(n); i++){
        if(n % i == 0){
            cout << i << endl;
            return 0;
        }
    }

    if(n % 2 == 0 and n > 4){
        cout << n / 2 << endl;
    }else{
        cout << n << endl;
    }


    return 0;
}