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

#define all(container) container.begin(), container.end()
#define sortall(container) (sort(container.begin(), container.end()))
#define yn(cond) ((cond) ? (cout << "Yes" << endl) : (cout << "No" << endl))
#define YN(cond) ((cond) ? (cout << "YES" << endl) : (cout << "NO" << endl))

typedef long long       ll;
typedef vector<int>     vi;
typedef vector<ll>      vll;
typedef vector<double>  vd;
typedef vector<bool>    vb;
typedef vector<string>  vs;
typedef vector<char>    vc;
typedef pair<int, int>  pii;
typedef pair<ll, ll>    pll;
typedef vector<pii>     vpii;
typedef vector<pll>     vpll;
typedef vector<vll>		vvll;
typedef vector<vi>		vvi;
typedef vector<vb>		vvb;
typedef vector<vs>		vvs;
typedef vector<vc>		vvc;

typedef struct edge_ {
	ll to;
	ll cost;
} edge;

typedef struct point_ {
	ll x, y;
	point_(ll x = 0, ll y = 0) : x(x), y(y) {}
} point;

template <typename T>
using mat2d = vector<vector<T>>;

constexpr double	PI = 3.14159265358979323846;
constexpr ll		INF = 1 << 15;
constexpr ll		MOD = (ll)1e9 + 7;
constexpr double	EPS = 1e-7;
constexpr int		dy4[4] = { 0, 1, 0, -1 };
constexpr int		dx4[4] = { 1, 0, -1, 0 };
constexpr int		dy8[8] = { 0, 1, 1, 1, 0, -1, -1, -1 };
constexpr int		dx8[8] = { 1, 1, 0, -1, -1, -1, 0, 1 };

template<typename T>
istream& operator >> (istream& is, vector<T>& vec) {
	for (T& x : vec) is >> x;
	return is;
}

template<typename T>
ostream& operator << (ostream& os, const vector<T>& vec) {
	for (const T& x : vec) os << x << " ";
	return os;
}

template<typename S, typename T>
istream& operator >> (istream& is, pair<S, T>& p) {
	is >> p.first >> p.second;
	return is;
}

istream& operator >> (istream& is, point& p) {
	is >> p.x >> p.y;
	return is;
}

template<typename S, typename T>
ostream& operator << (ostream& os, const pair<S, T>& p) {
	os << "{" << p.first << " " << p.second << "}";
	return os;
}

ostream& operator << (ostream& os, const edge e) {
	os << "{to: " << e.to << ", cost: " << e.cost << "}";
	return os;
}

ostream& operator << (ostream& os, const point& p) {
	os << "(" << p.x << " " << p.y << ")";
	return os;
}

/******************************************************************************/
/**********************         Don't make WA !!         **********************/
/******************************************************************************/



int main()
{
	ll N, K;
	cin >> N >> K;
	vll A(N);
	cin >> A;

	vll count(40, 0);
	for (int i = 0; i < N; i++) {
		ll a = A[i];
		int bit = 0;
		while (a > 0) {
			count[bit] += (a & 1);
			bit++;
			a >>= 1;
		}
	}

	vi X_best(40, 0);
	for (int i = 0; i < 40; i++) {
		if (count[i] >= (N + 1) / 2)
			X_best[i] = 0;
		else
			X_best[i] = 1;
	}


	ll ans = 0;
	for (int i = 0; i < N; i++)
		ans += A[i] ^ K;

	for (int i = 39; i >= 0; i--) {
		ll X = 0;
		// i+1~39ビット目まではKと同じ
		for (int j = 39; j >= i + 1; j--)
			X += ((K >> j) & 1) * pow(2, j);

		// 0~i-1ビット目までは最適なもの
		for (int j = i - 1; j >= 0; j--)
			X += X_best[j] * pow(2, j);

		if (X > K) continue;

		ll tmp = 0;
		for (int j = 0; j < N; j++) {
			tmp += A[j] ^ X;
		}
		ans = max(ans, tmp);
	}



	cout << ans << endl;

	return 0;
}

Measured memory_bytes: 1024