G-Meximum GCD

///////////////          PRANTA KUMER PANDIT            ///////////////
//                      Test Case Less Template                       ||
//                                                                    ||
//      BANGLADESH  UNIVERSITY OF BUSINESS AND TECHNOLOGY             ||
//                          INTAKE 52                                 ||
//                      DEPARTMENT OF CSE                             ||
//||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
//                      So, WELCOME TO ISHAN'S PERADISE           //
//                (-.-) Want to be a Secret tool of next ICPC  (-.-)  //
 
#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
#define pb   push_back
#define yes   cout<<"YES"<<endl
#define no   cout<<"NO"<<endl
#define all(x) (x).begin(), (x).end()
#define gcd(a,b)      __gcd(a,b)
#define lcm(a,b)  (a*b)/__gcd(a,b)
#define optimize() ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
int main() {
    optimize();
    int n, k;
    cin >> n >> k;
    if (n < 1 || n > 200000 || k < 1 || k > n) {
        cout << 1 << '\n';
        return 0;
    }
    vector<int> f(1000001, 0);
    for (int i = 0; i < n; ++i) {
        int a;
        cin >> a;
        if (a < 1 || a > 1000000) continue;
        f[a]++;
    }
    vector<int> da;
    for (int i = 1; i <= 1000000; ++i) {
        if (f[i]) {
            for (int d = 1; d * d <= i; ++d) {
                if (i % d == 0) {
                    da.pb(d);
                    if (d * d != i) da.pb(i / d);
                }
            }
        }
    }
    sort(all(da), greater<int>());
    da.erase(unique(all(da)), da.end());
    for (int g : da) {
        int count = 0;
        for (int m = g; m <= 1000000; m += g) {
            count += f[m];
        }
        if (count >= k) {
            cout << g << '\n';
            return 0;
        }
    }
    cout << 1 << '\n';
    return 0;
}
//                                   THANKS                             //