#include <bits/stdc++.h>

using namespace std;

int N, K;

int can[200005];

int main() {
    cin >> N >> K;
    vector<int> values(N);
    for (int i = 0; i < N; i++) {
        cin >> values[i];
        can[i] = 1;
    }
    int res = 0;
    for(int i=30;i>=0;i--){
        int mask = 1<<i;
        int counter = 0;
        for(int j=0;j<N;j++){
            if(can[j] && (mask&values[j])){
                counter++;
            }
        }
        if(counter >= K){
            res += mask;
            for(int j=0;j<N;j++){
                if(!(mask&values[j])){
                    can[j] = 0;
                }
            }
        }
    }
    cout << res << endl;

    return 0;
}