#include <vector>
#include<iostream>
#include <algorithm>
#include <cmath>
#include <iomanip>
#include <fstream>
#include <string>
#include <set>
#include <deque>
#include <queue>
#include <map>
#include <bitset>
#include <random>
#include <cassert>
#include <unordered_map>
#include <unordered_set>
using namespace std;
typedef long long             ll;
typedef unsigned long long     ull;
typedef long double            ld;
#define endl              "\n"
#define all(a)            a.begin(), a.end()
#define allr(a)           a.rbegin(), a.rend()
#define pb                push_back
#define F                 first
#define S             second
ll gcd(ll a, ll b) {
    while (b != 0) {
        ll tmp = a % b;
        a = b;
        b = tmp;
    }
    return a;
}
ll get_kek(ll left, ll right, vector<ll>& log, vector <vector<ll>>& sparce) {
    ll len = right - left + 1;
    ll level = log[len];
    return gcd(sparce[level][left], sparce[level][right - (1 << level) + 1]);
}
void solve() {
    ll k,n;
    cin >> n >> k;
    vector<ll> a(n);
    for (ll i = 0; i < n; i++) {
        cin >> a[i];
    }
    vector <vector<ll>> sparce(1, vector <ll>(1 + n));
    for (ll i = 1; i <= n; i++) {
        sparce[0][i] = a[i-1];
    }
    for (ll len = 1; len * 2 <= n; len *= 2) {
        sparce.push_back(sparce.back());
        for (ll i = 1; i + len <= n; i++) {
            sparce.back()[i] = gcd(sparce.back()[i], sparce.back()[i + len]);
        }
    }
    vector <ll> log(1 + n, 0);
    for (ll i = 2; i <= n; i++) log[i] = log[i >> 1] + 1;
    ll mx = -1e18;
    for (ll i = 0; i <= n - k; i++) {
        mx = max(mx, get_kek(i+1, i + k, log, sparce));
    }
    cout << mx << endl;
}

signed main() {
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);
    ll t = 1;
    //cin >> t;
    while (t--) {
        solve();
    }
}