#include <bits/stdc++.h>
#define ll long long
#define REP(i, n) for(int i=0;i<n;i++)
#define MOD ((ll) 4503599627370551)

using namespace std;

int n, k;
int arr[1000000];

int main(){
    cin >> n;
    cin >> k;
    REP(i, n) cin >> arr[i];

    int best = 0;

    for(int i=29;i>=0;i--){
        int s = 0;
        REP(j, n) {
            if(arr[j] & (1<<i)) s++;
        }
        if (s < k) continue;
        int p = 0;
        REP(j, n){
            if(arr[j] & (1<<i)) {
                arr[p] = arr[j];
                p++;
            }
        }
        best |= (1<<i);
        n = s;
    }

    cout << best << endl;
}