#include <bits/stdc++.h>
using namespace std;

const int N = 2e5+3;

int n, k;

int a[N];
int niz[30];
int sajz[30];
multiset<int> s[31];

multiset<int> presjek(multiset<int> a, multiset<int> b) {
	multiset<int> ret;
	for (const auto &e: a) {
		if (ret.count(e)) continue;
		for (int i = 0; i < (int)min(b.count(e), a.count(e)); ++i)
			ret.insert(e);
	}
	return ret;
}

int main() {
	scanf("%d %d", &n, &k);
	for (int i = 0; i < n; ++i) {
		scanf("%d", a+i);
	}
	for (int i = 0; i <= 30; ++i) {
		for (int j = 0; j < n; ++j) {
			if (a[j] & (1<<i)) {
				//niz[i] &= a[j];
			//	++sajz[i];
				s[i].insert(a[j]);  //zasto a[j] a ne samo j
			}
		}
	}
	int poc = 0;
	for (int i = 30; i >= 0; --i) {
		//if (sajz[poc] >= k) {
		//	break;
		//}
		if ((int)s[i].size() >= k) {
			poc = i;
			break;
		}
	}
	//int tmp = niz[poc];
	multiset<int> q(s[poc].begin(), s[poc].end());
	for (int i = poc-1; i >= 0; --i) {
		//if (__builtin_popcount(tmp & niz[i]) >= k) {
			//tmp &= niz[i];
		//}
		auto t = presjek(q, s[i]);
		if ((int)t.size() >= k) {
			q = t;
		}
	}
	if ((int)q.size() >= k) {
		//printf("%d\n", (int)q.size());
		int ans = *q.begin();
		for (const auto &e: q) {
			//printf("%d ", e);
			ans &= e;
		}
		printf("%d", ans);
	} else {
		printf("0");
	}
	
	return 0;
}