#include <bits/stdc++.h>
#include<iostream>
#include<iomanip>
#include<string>
#include<algorithm>
#include<vector>
#include<set>
#include<list>
#include<queue>
#include<math.h>
#include<bitset>
using ll = long long;
using namespace std;

int main()
{
    ll n, fac=2;
    cin >> n;
    while (fac*fac <= n){
        if (fac > 2 && !(n%fac)){
            cout << fac << endl;
            return 0;
        }
        if (!(n%fac)) n /= fac;
        else fac++;
    }
}