#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using Edge = pair<int, int>;
using Graph = vector<vector<Edge>>;
#define REP(i, n) for (int i = 0; i < (n); ++i)
#define SORT(v) sort((v).begin(), (v).end())
#define RSORT(v) sort((v).rbegin(), (v).rend())
const ll MOD = 1000000007;
const ll nmax = 8;
const ll INF = 1e9;
bool graph[nmax][nmax];
vector<vector<ll>> dist = vector<vector<ll>>(nmax, vector<ll>(nmax, INF));
void warshall_floyd(ll n)
{
    for (size_t i = 0; i < n; i++)
    {
        for (size_t j = 0; j < n; j++)
        {
            for (size_t k = 0; k < n; k++)
            {
                dist[j][k] = min(dist[j][k], dist[j][i] + dist[i][k]);
            }
        }
    }
}

class UnionFind
{
public:
    vector<ll> Parent;

    UnionFind(ll N)
    {
        Parent = vector<ll>(N, -1);
    }
    ll find(ll A)
    {
        if (Parent[A] < 0)
            return A;
        return Parent[A] = find(Parent[A]);
    }

    ll size(ll A)
    {
        return -Parent[find(A)];
    }

    bool Union(ll A, ll B)
    {
        A = find(A);
        B = find(B);
        if (A == B)
        {
            return false;
        }
        if (size(A) < size(B))
            swap(A, B);

        Parent[A] += Parent[B];
        Parent[B] = A;

        return true;
    }
};

ll gcd(ll a, ll b)
{
    if (b == 0)
        return a;
    return gcd(b, a % b);
}

ll lcm(ll a, ll b)
{
    ll g = gcd(a, b);
    return a / g * b;
}

ll mulMod(ll a, ll b)
{
    return (((a % MOD) * (b % MOD)) % MOD);
}

ll powMod(ll a, ll p)
{
    if (p == 0)
    {
        return 1;
    }
    else if (p % 2 == 0)
    {
        ll half = powMod(a, p / 2);
        return mulMod(half, half);
    }
    else
    {
        return mulMod(powMod(a, p - 1), a);
    }
}

ll ceil(ll a, ll b)
{
    return (a + b - 1) / b;
}

void solve(long long N, long long K, std::vector<long long> A)
{

    if (K == 0)
    {
        ll ans = 0;
        for (int i = 0; i < N; i++)
        {
            ans += A[i];
        }
        cout << ans << endl;
        return;
    }
    ll copy = (ll)pow(10,12);
    ll digit = 0;

    while (copy != 0)
    {
        digit++;
        copy /= 2;
    }
    ll tmp = 0;
    ll ans = 0;
    for (int i = digit; i >= 1; i--)
    {
        int cntZero = 0;
        int cntOne = 0;

        for (int j = 0; j < N; j++)
        {
            if (A[j] & (ll)pow(2, i - 1))
            {
                cntOne++;
            }
            else
            {
                cntZero++;
            }
        }
        if (K < tmp + pow(2, i - 1))
        {
            ans += (ll)pow(2, i - 1) * cntOne;
        }
        else
        {

            if (cntZero == cntOne)
            {
                ans += (ll)pow(2, i - 1) * cntZero;
            }
            else if (cntZero < cntOne)
            {
                ans += (ll)pow(2, i - 1) * cntOne;
            }
            else
            {
                ans += (ll)pow(2, i - 1) * cntZero;
                tmp += pow(2, i - 1);
            }
        }
    }
    cout << ans << endl;
}

int main()
{
    long long N;
    scanf("%lld", &N);
    long long K;
    scanf("%lld", &K);
    std::vector<long long> A(N);
    for (int i = 0; i < N; i++)
    {
        scanf("%lld", &A[i]);
    }
    solve(N, K, std::move(A));
    return 0;
}


Measured memory_bytes: 1024