#include <algorithm>
#include <cstdio>
#include <iostream>
#include <map>
#include <math.h>
#include <queue>
#include <set>
#include <sstream>
#include <stack>
#include <string>
#include <vector>
#include <time.h>
using namespace std;

#define ll long long
#define INF (1 << 30)
#define INFLL (1LL << 60)

int main() {
	ll n;
	bool flag = true;
	cin >> n;
	for(ll i = 3;i <= n / 2;i++){
		if(n % i == 0){
			cout << i << endl;
			flag = false;
			break;
		}
	}
	if(flag) cout << n << endl;
	return 0;
}