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

#define LL long long
#define LD long double
#define PII pair<int, int>
#define VI vector<int>
#define VPII vector<PII>
#define f first
#define s second
#define MP make_pair
#define PB push_back
#define endl '\n'
#define SIZ(c) (int)(c).size()
#define ALL(c) (c).begin(), (c).end()
#define REP(i, n) for (int i = 0; i < (int)(n); i++)
#define FOR(i, b, e) for (int i = (b); i <= (int)(e); i++)
#define FORD(i, b, e) for (int i = (b); i >= (int)(e); i--)
#define ll LL
#define st f
#define nd s
#define mp MP
#define pb PB
#define eb emplace_back
#define siz(c) SIZ(c)
const int inf = 1e9 + 7;
const LL INF = 1e18L + 7;

#define sim template<class n
sim, class s> ostream & operator << (ostream &p, pair<n, s> x)
{return p << "<" << x.f << ", " << x.s << ">";}
sim> auto operator << (ostream &p, n y) ->
typename enable_if<!is_same<n, string>::value, decltype(y.begin(), p)>::type
{int o = 0; p << "{"; for (auto c : y) {if (o++) p << ", "; p << c;} return p << "}";}
void dor() {cerr << "\n";}
sim, class...s> void dor(n p, s...y) {cerr << p << " "; dor(y...);}
sim, class s> void mini(n &p, s y) {if (p > y) p = y;}
sim, class s> void maxi(n &p, s y) {if (p < y) p = y;}

#ifdef DEB
#define debug(...) dor(__FUNCTION__, ":", __LINE__, ": ", __VA_ARGS__)
#else
#define debug(...)
#endif

#define I(x) #x " =", (x), " "

int n, k;

VI curr;

int32_t main()
{
	ios_base::sync_with_stdio(0);
	cin.tie(0);
	
	cin >> n >> k;
	
	for(int i = 1; i <= n; ++i)
	{
		int x;
		cin >> x;
		curr.pb(x);
	}
	
	for(int b = 29; b >= 0; --b)
	{
		int ile = 0;
		
		for(auto it:curr)
		{
			if(it&(1<<b))
				++ile;
		}
		
		if(ile<k)
			continue;
		else
		{
			for(int i = 0; i < siz(curr); ++i)
			{
				if(!(curr[i]&(1<<b)))
				{
					swap(curr[i], curr.back());
					curr.pop_back();	
					--i;
				}
			}
		}
	}
	
	int ans = curr[0];
	
	for(auto it:curr)
		ans &= it;
		
	cout << ans << endl;
}