#include <iostream>
#include <cmath>
using namespace std;
typedef long long ll;

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