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#include "bits/stdc++.h"

using namespace std;
#define PB push_back
#define LL long long
#define int LL
#define FOR(i,a,b) for (int i = (a); i <= (b); i++)
#define FORD(i,a,b) for (int i = (a); i >= (b); i--)
#define REP(i,n) FOR(i,0,(int)(n)-1)
#define st first
#define nd second
#define ALL(x) (x).begin(), (x).end()
#define SZ(x) ((int)(x).size())
#define VI vector<int>
#define PII pair<int,int>
#define LD long double

template<class C> void mini(C& a4, C b4) { a4 = min(a4, b4); }
template<class C> void maxi(C& a4, C b4) { a4 = max(a4, b4); }

template<class TH> void _dbg(const char *sdbg, TH h){cerr<<sdbg<<"="<<h<<"\n";}
template<class TH, class... TA> void _dbg(const char *sdbg, TH h, TA... a) {
  while(*sdbg!=',')cerr<<*sdbg++;
  cerr<<"="<<h<<",";
  _dbg(sdbg+1, a...);
}

template<class T> ostream &operator<<(ostream &os, vector<T> V){
  os<<"[";for(auto vv:V)os<<vv<<",";return os<<"]";
} 

template<class L, class R> ostream &operator<<(ostream &os, pair<L,R> P) {
  return os << "(" << P.st << "," << P.nd << ")";
}

template<class A, class B> ostream &operator<<(ostream &os, map<A,B> V){
  os<<"[";for(auto vv:V)os<<vv<<",";return os<<"]";
} 

#ifdef LOCAL
#define debug(...) _dbg(#__VA_ARGS__, __VA_ARGS__)
#else
#define debug(...) (__VA_ARGS__)
#define cerr if(0)cout
#endif

int get_result(map<int, int> & mapka, int idx){
  auto it = mapka.find(idx);
  return it == mapka.end() ? LLONG_MIN : it->nd;
}

void set_result(map<int,int> & mapka, int idx, int val){
  int old_val = get_result(mapka, idx);
  mapka[idx] = max(old_val, val);
}

int32_t main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  int n,m;
  cin>>n>>m;
  int max_bit = 0;
  while(1LL << (max_bit + 1) <= m){
    max_bit++;
  }
  debug(max_bit);
  VI a(n);
  REP(i, n){
    cin>>a[i];
  }
  // last num, result
  map<int,int> states = {{-1, 0}};
  REP(i, n){
    map<int,int> nstates;
    for(PII p : states){
      int min_num = p.st + 1;
      if(min_num > m)
        continue;
      int res = p.nd;

      int orig_bits = __builtin_popcountll(min_num);
      //nic nie robimy
      set_result(nstates, min_num, orig_bits * a[i] + res);

      if(a[i] > 0){
        //wieksza liczba bitow
        int cur_num = min_num;
        int neg_cur_num = ~cur_num;
        FOR(cur_bits, orig_bits + 1, max_bit + 1){
          int smallest_bit = neg_cur_num & -neg_cur_num;
          neg_cur_num ^= smallest_bit;
          cur_num ^= smallest_bit;
          if(cur_num > m)
            break;
          if(cur_bits < max_bit - 30)
              continue;
          set_result(nstates, cur_num, cur_bits * a[i] + res);
        }
      }
      if(a[i] < 0){
        //mniejsza liczba bitow
        int recent_old_bits = orig_bits;
        int cur_num = min_num;
        while(cur_num < m){
          cur_num ^= cur_num & -cur_num;
          if(!cur_num)
            break;
          cur_num += cur_num & -cur_num;
          if(cur_num > m)
            break;
          int tmp_bits = __builtin_popcountll(cur_num);
          int tmp_num = cur_num;
          FOR(cur_bits, tmp_bits, recent_old_bits - 1){
            if(max_bit < 40 || cur_bits <= 10)
              set_result(nstates, tmp_num, tmp_bits * a[i] + res);
            tmp_num |= ~tmp_num & -(~tmp_num);
            if(tmp_num > m)
              break;
          }
          recent_old_bits = tmp_bits;
        }
      }
    }
    map<int,int> convex_nstates;
    int best_res = LLONG_MIN;
    for(auto p : nstates){
      if(p.nd > best_res){
        convex_nstates[p.st] = p.nd;
        best_res = p.nd;
      }
    }
    states = convex_nstates;
    debug(SZ(states));
  }
  int res = LLONG_MIN;
  for(auto p : states){
    maxi(res, p.second);
  }
  cout<<res<<"\n";
}