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

typedef long long ll;
#define REP(i,n) for(int i=0,_n=(int)(n);i<_n;++i)
#define ALL(v) (v).begin(),(v).end()
#define CLR(t,v) memset(t,(v),sizeof(t))
template<class T1,class T2>ostream& operator<<(ostream& os,const pair<T1,T2>&a){return os<<"("<<a.first<<","<<a.second<< ")";}
template<class T>void pv(T a,T b){for(T i=a;i!=b;++i)cout<<(*i)<<" ";cout<<endl;}
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;}

ll nextLong() { ll x; scanf("%lld", &x); return x;}

int main2() {
  int N = nextLong();
  int T = nextLong();
  vector<int> A(N);
  REP(i, N) A[i] = nextLong();

  map<int, ll> dp;
  dp[T] = 0;
  REP(i, N) {
    map<int, ll> ndp;
    for (auto p : dp) {
      int t = p.first;
      ll score = p.second;
      REP(k, 2) {
        int nt = (k == 0) ? (t & A[i]) : (t | A[i]);
        ll nscore = score + abs(t - nt);
        if (ndp.count(nt) == 0 || ndp[nt] < nscore) {
          ndp[nt] = nscore;
        }
      }
    }
    swap(dp, ndp);
  }

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

int main() {

#ifdef LOCAL
  for (;!cin.eof();cin>>ws)
#endif
    main2();
  return 0;
}