#ifndef LOCAL
#pragma GCC optimize("O3")
#endif
#include <bits/stdc++.h>
using namespace std;

#define sim template < class c
#define ris return * this
#define mor > muu & operator << (
#define R22(r) sim > typename \
  enable_if<1 r sizeof dud<c>(0), muu&>::type operator<<( c g) {
sim > struct rge { c b, e; };
sim > rge<c> range(c h, c n) { return {h, n}; }
sim > auto dud(c * r) -> decltype(cerr << *r);
sim > char dud(...);
struct muu {
	#ifdef LOCAL
	stringstream a;
	~muu() { cerr << a.str() << endl; }
	R22(<) a << boolalpha << g; ris; }
	R22(==) ris << range(begin(g), end(g)); }
	sim, class b mor pair < b, c> r) { ris << "(" << r.first << ", " << r.second << ")"; }
	sim mor rge<c> u) {
		a << "[";
		for (c i = u.b; i != u.e; ++i) 
			*this << ", " + 2 * (i == u.b) << *i;
		ris << "]";
	}
#else
sim mor const c&) { ris; }
#endif
muu & operator()() { ris; }
};
#define imie(r...) "[" #r ": " << (r) << "] "
#define debug (muu() << __FUNCTION__ << "#" << __LINE__ << ": ")


void solve() {
	int n, k;
	cin >> n >> k;
	vector<int> v(n);
	for (int& a : v) {
		cin >> a;
	}
	int ans = 0;
	for (int i = 30; i >= 0; i--) {
		int M = 1 << i;
		int x = 0;
		for (int a : v) x += ((a & M) != 0);
		if (x >= k) {
			vector<int> w;
			for (int a : v) if (a & M) w.push_back(a);
			ans |= M;
			v = w;
		}
	}
	cout << ans << "\n";
}

int main() {
	ios_base::sync_with_stdio(0);
	solve();
}