#include <iostream>
#include <vector>
#include <algorithm>
using namespace std;

vector<int> arr;
int sort_bit = 30;

bool func(int a, int b){
    return (a & (1 << sort_bit)) > (b & (1 << sort_bit));
}

int main(){
    int N, K;

    cin >> N >> K;
    arr.resize(N);
    for(int i = 0; i < N; i++){
        cin >> arr[i];
    }

    for(int i = 30; i >= 0; --i) {
        if(arr.size() < K) break;
        sort_bit = i;
        sort(arr.begin(), arr.end(), func);
        int counter = 0;
        for(int x = 0; x < arr.size(); ++x){
            if((arr[x] & (1 << sort_bit)) != 0){
                counter++;
            }
        }

        if(counter >= K){
            arr.resize(counter);
        }
    }

    if(arr.size() == 0){
        cout << 0;
        return 0;
    }

    int rez = arr[0];
    for(int i = 1; i < K; ++i){
        rez &= arr[i];
    }
    cout << rez;

    return 0;
}