#include <bits/stdc++.h>

using namespace std;

int main() {
    cin.sync_with_stdio(false);
    cin.tie(NULL);
    int N,K;
    cin >> N >> K;
    vector<int> T0(N);
    for (int i = 0; i < N; i++) {
        cin >> T0[i];
    }
    int RET = 0;
    for (int bit = 30; bit >= 0; bit--) {
        // osszegezzuk
        int s = 0;
        int bitval = 1<<bit;
        for (int a: T0) {
            if (a&bitval)
                s++;
        }
        if (s >= K) {
            RET |= bitval;
            vector<int> T1;
            T1.reserve(s);
            for (int a: T0) {
                if (a&bitval)
                    T1.push_back(a);
            }
            T0 = move(T1);
        }
    }
    cout << RET << endl;
}