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

using ll = long long;

struct result {
  ll res;
  ll m;

  bool operator<(result const& b) const {
    if (m != b.m) return m < b.m;
    return res < b.res;
  }
};

set<result> current, nxt;

int n, lg;
ll m;

void maybeInsert(result r) {
  auto it = nxt.upper_bound(r);
  if (it != nxt.end() && it->m == r.m) {
    return;
  }
  while (it != nxt.end() && it->res <= r.res) {
    it = nxt.erase(it);
  }
  if (it == nxt.begin()) {
    nxt.insert(it, r);
    return;
  }
  it--;
  if (it->m == r.m) {
    it = nxt.erase(it);
    if (it == nxt.begin()) {
      return;
    }
    it--;
  }
  if (it->res >= r.res) {
    return;
  }
  it++;
  nxt.insert(it, r);
}

int main() {
  scanf("%d %lld", &n, &m);
  for (ll t = m; t; t /= 2) {
    lg++;
  }
  for (int i = 0; i < n; i++) {
    ll a;
    scanf("%lld", &a);
    if (i == 0) {
      current.insert({0, 0});
      for (int k = 0; k < lg; k++) {
        ll t = (1ll<<(k+1)) - 1;
        if (t <= m) {
          current.insert({a * (k+1), t});
        }
      }
    } else {
      for (auto r : current) {
        vector<int> used(lg+1, 0);
        int pc = __builtin_popcountll(r.m);
        for (int k2 = 0; k2 < lg; k2++) {
          ll m1 = r.m | ((1ll<<(k2+1)) - 1);
          pc += (r.m >> k2) % 2 == 0;
          if (m1 > r.m && m1 <= m) {
            if (!used[pc]) {
              maybeInsert({r.res + a * pc, m1});
              used[pc] = 1;
            }
          }
        }

        for (int k = 0; k < lg; k++) {
          ll m2 = ((r.m >> k) | 1) << k;
          if (m2 > r.m && m2 <= m) {
            pc = __builtin_popcountll(m2);
            int pc0 = pc;
            if (!used[pc]) {
              maybeInsert({r.res + a * pc, m2});
              used[pc] = 1;
              for (int k2 = 0; k2 < lg; k2++) {
                ll m1 = m2 | ((1ll<<(k2+1)) - 1);
                pc += (m2 >> k2) % 2 == 0;
                if (m1 <= m) {
                  if (!used[pc]) {
                    maybeInsert({r.res + a * pc, m1});
                    used[pc] = 1;
                  } else if (pc >= pc0) break;
                }
              }
            }
          }
        }
      }
      current.swap(nxt);
      nxt.clear();
    }
  }
  printf("%lld\n", accumulate(current.begin(), current.end(), -4000000000000000000ll, [](ll res, result r) {
    return max(res, r.res);
  }));
}