#include <iostream>
#include <algorithm>
#include <string>
#include <vector>
#include <cmath>
#include <map>
#include <queue>
#include <iomanip>
#include <set>
#include <tuple>
#define mkp make_pair
#define mkt make_tuple
#define rep(i,n) for(int i = 0; i < (n); ++i)
#define all(v) v.begin(),v.end()
using namespace std;
typedef long long ll;
const ll MOD=1e9+7;
template<class T> void chmin(T &a,const T &b){if(a>b) a=b;}
template<class T> void chmax(T &a,const T &b){if(a<b) a=b;}

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

  int N;
  ll T;
  cin>>N>>T;
  vector<ll> A(N);
  rep(i,N) cin>>A[i];

  map<ll,ll> dp;
  dp[T]=0;
  for(int i=0;i<N;i++){
    map<ll,ll> ndp;
    for(auto m:dp){
      ll a=m.first;
      ll b=m.second;

      ll s=(a & A[i]);
      ll t=(a | A[i]);
      {
        chmax(ndp[s],b+a-s);
      }
      {
        chmax(ndp[t],b+t-a);
      }
    }
    dp=ndp;
  }

  ll ans=0;
  for(auto m:dp) chmax(ans,m.second);
  cout<<ans<<endl;

  return 0;
}