#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;

void factorization(ll n, vector<ll> &factors) {
    ll d = 2;
    while (n % d == 0) {
        n /= d;
        factors.push_back(d);
    }
    ll limit = (ll)sqrt(n) + 1;
    d = 3;
    while (d <= limit) {
        while (n % d == 0) {
            n /= d;
            factors.push_back(d);
        }
        d += 2;
    }
    if (n > 1) factors.push_back(n);
}


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

    ll N;
    cin >> N;
    vector<ll> factors;
    factorization(N, factors);
    
    for (auto &e: factors) {
        if (e > 2) {
            cout << e << endl;
            break;
        }
    }
    return 0;
}