#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using Vi = vector<int>;
using Pii = pair<int,int>;
#define mp make_pair
#define pb push_back
#define x first
#define y second
#define rep(i,b,e) for(int i = (b); i < (e); i++)
#define each(a, x) for(auto& a : (x))
#define all(x) (x).begin(),(x).end()
#define sz(x) int((x).size())

int main() {
	cin.sync_with_stdio(0); cin.tie(0);
	cout << fixed << setprecision(12);

	int n, k; cin >> n >> k;

	vector<ll> elems(n), tmp;
	each(e, elems) cin >> e;

	ll ans = 0;

	for (int bit = 29; bit >= 0; bit--) {
		tmp.clear();

		each(e, elems) {
			if ((e >> bit) & 1) {
				tmp.pb(e);
			}
		}

		if (sz(tmp) >= k) {
			elems = tmp;
			ans |= 1ll<<bit;
		}
	}

	cout << ans << endl;
	return 0;
}