#include <iostream>
#include <vector>
#include <algorithm>
using namespace std;

#define RREP(i,s,e) for (i = e-1; i >= s; i--)
#define rrep(i,n) RREP(i,0,n)
#define REP(i,s,e) for (i = s; i < e; i++)
#define rep(i,n) REP(i,0,n)
#define INF 1e8

typedef long long ll;

int main() {
    ll ans, n;
    cin >> n;
    REP (ans,3,sqrt(n)+1) {
        if (n % ans == 0) {
            cout << ans << endl;
            return 0;
        }
    }
    if (n % 2 == 0 && n / 2 != 2)
        cout << n / 2 << endl;
    else
        cout << n << endl;
    return 0;
}