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

typedef long long LL;
typedef long double LD;
typedef pair < int, int > PII;
typedef pair < LL, LL > PLL;

#define all(x) (x).begin(), (x).end()
#define sz(x) (int)(x).size()

const int N = 2e5 + 7;

int n, k;
vector < int > vec;

int main()
{
	ios_base::sync_with_stdio(0); cin.tie(0);

	cin >> n >> k;
	for(int i = 1; i <= n; i++)
	{
		int x; cin >> x;
		vec.push_back(x);
	}
	
	int ans = 0;
	for(int b = 29; b >= 0; b--)
	{
		vector < int > zer, one;
		for(auto x: vec)
		{
			if(x & (1 << b))
				one.push_back(x);
			else
				zer.push_back(x);
		}
		if(sz(one) >= k)
		{
			vec = one;
			ans += (1 << b);
		}
	}
	cout << ans << "\n";
	
	return 0;
}