#include <iostream>
using namespace std;

int main(){
    int n, k, res = 0;
    cin >> n >> k;

    int mus[n];
    bool ingr[n];
    for (int i = 0; i < n; i++){
        ingr[i] = true;
        cin >> mus[i];
    }

    for (int d = 29; d >= 0; d--){
        int count = 0;
        for (int i = 0; i < n; i++){
            if (!ingr[i])
                continue;
            if ((1 << d) & mus[i])
                count++;
        }

        if (count >= k){
            res += (1 << d);
            for (int i = 0; i < n; i++){
                if (!ingr[i])
                    continue;
                if (((1 << d) & mus[i]) == 0)
                    ingr[i] = false;
            }
        }
    }

    cout << res << endl;
}