#include <bits/stdc++.h>

using namespace std;

int main() {
    ios_base::sync_with_stdio(0);

    int n, k;
    cin >> n >> k;

    vector<int> l(n);
    for (int i = 0; i < n; i++)
        cin >> l[i];

    int res = 0;
    vector<bool> t(n, true);
    for (int i = 30; i >= 0; i--) {
        int cnt = 0;
        for (int j = 0; j < n; j++) {
            if (t[j]  &&  (l[j] & (1 << i)))
                cnt++;
        }
        if (cnt < k)
            continue;
        for (int j = 0; j < n; j++) {
            if ((l[j] & (1 << i)) == 0)
                t[j] = false;
        }
        res += (1 << i);
    }
    cout << res << endl;
    return 0;
}