#include <iostream>
#include <vector>
#include <algorithm>
#include <map>
#include <string>
#include <queue>
#include <stack>
#include <math.h>
#include <set>
#include <cstdio>
#define ALL(obj) (obj).begin(),(obj).end()
#define RALL(obj) (obj).rbegin(),(obj).rend()
#define P pair<int, int>

#define MOD 1000000007
#define INF 1012345678
#define NINF (-2147483647-1)
#define LLINF 9223372036854775807
using ll = long long;
using namespace std;

int main() {
    ll N;
    cin >> N;
    bool b = false;
    for (ll i = 3; i*i <= N; i++)
    {
        if (N % i == 0) {
            cout << i << endl;
            b = true;
            break;
        }
    }
    if (!b) {
        cout << N << endl;
    }
    getchar(); getchar();
    return 0;
}