E: tree

#include <iostream>
#include <vector>
#include <algorithm>
#include <math.h>

using namespace std;

vector<int> vec;
int pow2 = 1;

int gsd(int a, int b) {
    return (b == 0 ? a : gsd(b, a % b));
}

int gcd(int a, int b) {
    return (b == 0 ? a : gcd(b, a % b));
}

int f(int l, int r, int lv, int rv, int v) {

    if (l <= lv && rv <= r) return vec[v];
    if (lv > r || rv < l) return 0;
    return gcd(f(l, r, lv, lv + (rv - lv) / 2, v * 2 ), f(l, r, lv + (rv - lv) / 2 + 1, rv, v * 2 + 1));

}

int main() {
    int n, k, news = 0;
    cin >> n >> k;



    while (pow(2, pow2) < n)
        pow2++;
    pow2++;

    vec.resize(pow(2, pow2), 0);

    for (int i = pow(2, pow2 - 1); i < pow(2, pow2 - 1) + n; i++)
        cin >> vec[i];

    for (int i = pow(2, pow2 - 1) - 1; i > 0; i--)
        vec[i] = gsd(vec[2 * i], vec[2 * i + 1]);

    for (int i = pow(2, pow2 - 1); i < pow(2, pow2) - k; i++) {
        news = max(news, f(i, i + k - 1, pow(2, pow2 - 1), pow(2, pow2) - 1, 1));
    }

    cout << news;
    return 0;
}