#include <iostream>
#include <stdio.h>
#include <cmath>
#include <algorithm>
#include <memory>
#include <map>
#include <vector>


using namespace std;

vector<vector<int>> napok(30);

    int ketto_hatvany[] = {
        1,
        2,
        4,
        8,
        16,
        32,
        64,
        128,
        256,
        512,
        1024,
        2048,
        4096,
        8192,
        16384,
        32768,
        65536,
        131072,
        262144,
        524288,
        1048576,
        2097152,
        4194304,
        8388608,
        16777216,
        33554432,
        67108864,
        134217728,
        268435456,
        536870912
    };

void magic(int band, int temp) {
    for (int i = 29; i >= 0; i--) {
        if (temp >= ketto_hatvany[i]) {
            temp -= ketto_hatvany[i];

            napok[i].push_back(band);
        } 
    } 
}

int n, k;
vector<int> aktual;
vector<int> aktual2;

int main() {

    cin >> n >> k;

    int temp;
    for (int i = 0; i < n; i++) {
        scanf("%d", &temp);
        magic(i, temp);
    }

/*
    for (int i = 0; i < 30; i++) {
        for (int j = 0; j < melyik_nap_meret[i]; j++) {
            cout << melyik_nap_mennyi[i][j] << " ";
        }
        cout << endl;
    }
*/
    int result = 0;
    int index_ = 0;

    for (int i = 29; i >= 0; i--) {
        if (napok[i].size() >= k) {
            aktual = napok[i];
            result += ketto_hatvany[i];

            index_ = i;
            break;
        }
    }

    for (int i = index_ - 1; i >= 0; i--) {

        aktual2 = napok[i];
        vector<int> res;

        std::set_intersection(aktual.begin(), aktual.end(),
            aktual2.begin(), aktual2.end(),
            std::back_inserter(res));            
        if (res.size() >= k) {
            aktual = res;
            result += ketto_hatvany[i];
        }
    }
    cout << result << endl;
    return 0;
}