#include <cstdio>
#include <cstring>
#include <iostream>
#include <string>
#include <cmath>
#include <bitset>
#include <vector>
#include <map>
#include <set>
#include <queue>
#include <deque>
#include <algorithm>
#include <complex>
#include <unordered_map>
#include <unordered_set>
#include <random>
#include <cassert>
#include <fstream>
#include <utility>
#include <functional>
#include <time.h>
#include <stack>
#include <array>
#define popcount __builtin_popcount
using namespace std;
using ll=long long;
typedef pair<int, ll> P;

int main()
{
    int n, t; cin>>n>>t;
    map<int, ll> dp;
    dp[t]=0;
    for(int i=0; i<n; i++){
        int a; cin>>a;
        map<int, ll> ndp;
        for(auto p:dp){
            int x=p.first;
            ndp[x&a]=max(ndp[x&a], p.second+x-(x&a));
            ndp[x|a]=max(ndp[x|a], p.second+(x|a)-x);
        }
        swap(dp, ndp);
    }
    ll mx=0;
    for(auto p:dp) mx=max(mx, p.second);
    cout<<mx<<endl;
    return 0;
}