#include<bits/stdc++.h>
using namespace std;
#define REP(i,m,n) for(int i=(int)(m) ; i < (int) (n) ; ++i )
#define rep(i,n) REP(i,0,n)
using ll = long long;
int main(){
    cin.tie(nullptr);
    ios::sync_with_stdio(false);
    int n;
    cin>>n;
    int t;
    cin>>t;
    map<int,ll> dp;
    dp[t]=0;
    rep(i,n){
        int x;
        cin>>x;
        map<int,ll> ndp;
        for(auto e:dp){
            ndp[e.first|x] = max(ndp[e.first|x],e.second +  (e.first|x) - e.first);
            ndp[e.first&x] = max(ndp[e.first&x],e.second +  e.first - (e.first&x));
        }
        dp.swap(ndp);
    }
    ll ma=0;
    for(auto e:dp)ma=max(e.second, ma);
    cout<<ma<<endl;
    return 0;
}