#include <iostream>
#include <vector>
#include <algorithm>
#include <cmath>

#define FORR(i,b,e) for(int i=(b);i<(int)(e);++i)
#define FOR(i,e) FORR(i,0,e)
#define ALL(c) begin(c), end(c)
#define dump(var) cerr << #var ": " << var << "\n"
#define dumpc(con) for(auto& e: con) cerr << e << " "; cerr<<"\n"

using namespace std;

typedef long long ll;


int main() {
    cin.tie(0);
    ios::sync_with_stdio(false);

    ll N;
    cin >> N;
    
    ll limit = (ll)sqrt(N) + 1;
    for (ll i=3; i <= limit; 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;
}