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// region standard
#pragma GCC optimize "-O3"

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

#pragma GCC diagnostic ignored "-Wunused-macros"

namespace std {
   // type_traits logical operations mock for C++11
#if __cplusplus < 201700L
   template <bool B>
   using bool_constant = integral_constant<bool, B>;
   template<typename...> struct conjunction : true_type { };
   template<typename B1> struct conjunction<B1> : B1 { };
   template<typename B1, typename... Bn>
   struct conjunction<B1, Bn...>
      : conditional<bool(B1::value), conjunction<Bn...>, B1>::type { };
   template<class...> struct disjunction : false_type { };
   template<class B1> struct disjunction<B1> : B1 { };
   template<class B1, class... Bn>
   struct disjunction<B1, Bn...>
      : conditional<bool(B1::value), B1, disjunction<Bn...>>::type  { };
   template<typename B>
   struct negation : bool_constant<!bool(B::value)> { };
#endif
}

#define guard(x) if (!(x))

#define _CAT(A, B) A ## B
#define CAT(A, B) _CAT(A, B)
#define _CAT3(A, B, C) A ## B ## C
#define CAT3(A, B, C) _CAT3(A, B, C)
#define _STR(...) #__VA_ARGS__
#define STR(...) _STR(__VA_ARGS__)
#define _FIRST(F, ...) F
#define FIRST(...) _FIRST(__VA_ARGS__, )
#define SKIP1(F, ...)  __VA_ARGS__
#define SKIP2(F, ...)  SKIP1(__VA_ARGS__, )
#define SKIP3(F, ...)  SKIP2(__VA_ARGS__, )
#define SKIP4(F, ...)  SKIP3(__VA_ARGS__, )
#define SKIP5(F, ...)  SKIP4(__VA_ARGS__, )
#define SKIP6(F, ...)  SKIP5(__VA_ARGS__, )
#define SKIP7(F, ...)  SKIP6(__VA_ARGS__, )
#define SKIP8(F, ...)  SKIP7(__VA_ARGS__, )
#define SKIP9(F, ...)  SKIP8(__VA_ARGS__, )
#define SKIP10(F, ...) SKIP9(__VA_ARGS__, )
#define SKIP11(F, ...) SKIP10(__VA_ARGS__, )
#define SKIP12(F, ...) SKIP11(__VA_ARGS__, )
#define SKIP(N, ...) CAT(SKIP, N)(__VA_ARGS__, )
#define COUNT(...) FIRST(SKIP12(__VA_ARGS__, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1))
#ifdef DEBUG
   #define MAGIC do { std::clog << boolalpha; } while(0)
   #define PRINT(msg) do { std::clog << "DBG:" << __LINE__ << ">  " << msg << std::endl; } while(0)
#else
   #define MAGIC do { ios_base::sync_with_stdio(false); cin.tie(nullptr); cout.tie(nullptr); } while(0)
   #define PRINT(msg) do { } while(0)
   #define clog DONT_USE_CLOG!!!!!!!
   #define cerr DONT_USE_CERR!!!!!!!
   #define endl DONT_USE_ENDL!!!!!!!
#endif
#define _DBG1(x, ...)  STR(x) << ": " << (x)
#define _DBG2(x, ...)  STR(x) << ": " << (x) << " \t" << _DBG1(__VA_ARGS__)
#define _DBG3(x, ...)  STR(x) << ": " << (x) << " \t" << _DBG2(__VA_ARGS__)
#define _DBG4(x, ...)  STR(x) << ": " << (x) << " \t" << _DBG3(__VA_ARGS__)
#define _DBG5(x, ...)  STR(x) << ": " << (x) << " \t" << _DBG4(__VA_ARGS__)
#define _DBG6(x, ...)  STR(x) << ": " << (x) << " \t" << _DBG5(__VA_ARGS__)
#define _DBG7(x, ...)  STR(x) << ": " << (x) << " \t" << _DBG6(__VA_ARGS__)
#define _DBG8(x, ...)  STR(x) << ": " << (x) << " \t" << _DBG7(__VA_ARGS__)
#define _DBG9(x, ...)  STR(x) << ": " << (x) << " \t" << _DBG8(__VA_ARGS__)
#define _DBG10(x, ...) STR(x) << ": " << (x) << " \t" << _DBG9(__VA_ARGS__)
#define _DBG11(x, ...) STR(x) << ": " << (x) << " \t" << _DBG10(__VA_ARGS__)
#define _DBG12(x, ...) STR(x) << ": " << (x) << " \t" << _DBG11(__VA_ARGS__)
#define _DBG(...) CAT(_DBG, COUNT(__VA_ARGS__))(__VA_ARGS__, )
#define DBG(...) PRINT(_DBG(__VA_ARGS__))
#define PDBG(msg, ...) PRINT(msg << _DBG(__VA_ARGS__))

#define ST first
#define ND second
#define EM emplace
#define EB emplace_back
#define IN insert
#define PB push_back
#define vec vector
#define umap unordered_map
#define nil nullptr
using ll = long long;
using ull = unsigned long long;
using ld = long double;
using str = string;
using PI = pair<int, int>;
using VI = vector<int>;
using VVI = vector<VI>;
using VLL = vector<ll>;

template <typename T, unsigned long N> char(&dim_helper(T(&)[N]))[N];
#define ASZ(x) ((ll)(sizeof(dim_helper((x)))))
#define SZ(x) ((ll)((x).size()))
#define ALL(x) std::begin((x)), std::end((x))
#define PAL(p) (p).ST, (p).ND

#define FI(e, v) for (auto const & e : (v))
#define _FS(i, s, n, r, type)  for (type i = s; r ? i > n : i < n; i += 1 - 2*r)
#define FS(i, s, n) _FS(i, (s), (n), ((s) > (n)), remove_cv<__typeof((n))>::type)
#define FR(i, n) FS(i, 0, (n))
#define _RS(i, s, n, r, type) for (type i = s; r ? i >= n : i <= n; i += 1 - 2*r)
#define RS(i, s, n) _RS(i, (s), (n), ((s) > (n)), remove_cv<__typeof((n))>::type)
#define RR(i, n) RS(i, 1, (n))


template <typename T>
inline T safemod(T x, T m) {
  return (x % m + m) % m;
}

template <typename T>
inline T mini(T & a, T const & b) {
   return a = min(a, b);
}
template <typename T>
inline T maxi(T & a, T const & b) {
   return a = max(a, b);
}

template <typename T>
inline T fpow(T a, ull b, T M) {
   T r(1);
   while (b > 0) {
      if (b & 1)  {
         r *= a;
         r %= M;
      }

      a *= a;
      a %= M;
      b >>= 1;
   }
   return r;
}


// ostream out ostream
template <typename Iter>
void ooo(Iter first, Iter last, char const * delim, ostream & os) {
   while (first != last) {
      os << *(first++) << delim;
   }
}

// ostream out
template <typename Iter>
inline void oo(Iter first, Iter last, char const * delim) {
   ooo(first, last, delim, cout);
}

// container ostream out
template <typename C>
inline void coo(C V, char const * delim) {
   ooo(ALL(V), delim, cout);
}

// infix out ostream
template <typename Iter>
void ioo(Iter first, Iter last, char const * delim, ostream & os) {
   goto delim_jmp;
   while (first != last) {
      os << delim;
      delim_jmp: os << *(first++);
   }
}

// infix out
template <typename Iter>
inline void io(Iter first, Iter last, char const * delim) {
   ioo(first, last, delim, cout);
}

// container infix out
template <typename C>
inline void cio(C V, char const * delim) {
   ioo(ALL(V), delim, cout);
}

#ifdef DEBUG
template<typename T, typename S>
ostream & operator << (ostream & os, pair<T, S> const & p) {
   return os << "(" << p.ST << ", " << p.ND << ")";
}
template<typename... Args>
ostream & operator << (ostream & os, multimap<Args...> const & S) {
   os << "{";
   ioo(ALL(S), ", ", os);
   return os << "}";
}
template<typename... Args>
ostream & operator << (ostream & os, map<Args...> const & S) {
   os << "{";
   ioo(ALL(S), ", ", os);
   return os << "}";
}
template<typename... Args>
ostream & operator << (ostream & os, multiset<Args...> const & S) {
   os << "{";
   ioo(ALL(S), ", ", os);
   return os << "}";
}
template<typename... Args>
ostream & operator << (ostream & os, set<Args...> const & S) {
   os << "{";
   ioo(ALL(S), ", ", os);
   return os << "}";
}
template<typename... Args>
ostream & operator << (ostream & os, vector<Args...> const & V) {
   os << "[";
   ioo(ALL(V), ", ", os);
   return os << "]";
}
template<typename... Args>
ostream & operator << (ostream & os, valarray<Args...> const & VA) {
   os << "[";
   ioo(ALL(VA), ", ", os);
   return os << "]";
}
#endif

// istream in istream
template <typename Iter>
void iii(Iter to, ll n, istream & is) {
   while(n--) {
      is >> *(to++);
   }
}

// istream in
template <typename Iter>
void ii(Iter to, ll const & n) {
   iii(to, n, cin);
}

// container istream in
template <typename C>
void cii(C & V, ll const & n) {
   iii(V.begin(), n, cin);
}

// container istream in
template <typename C>
C cii(ll const & n) {
   C V(n);
   iii(V.begin(), n, cin);
   return V;
}


template<typename WEIGHT, typename NODE = int>
struct _Node {
   NODE v;

   _Node() : _Node(0) { }
   _Node(NODE const _v) : v(_v) { }

   operator NODE () const {
      return v;
   }

   WEIGHT w() const;
   WEIGHT w(NODE u) const;
   WEIGHT w(_Node u) const {
      return w(u.v);
   }

   _Node & operator [] (NODE u) const;
   _Node & operator [] (_Node u) const {
      return operator [] (u.v);
   }

   friend istream & operator >> (istream & is, _Node & self) {
      return is >> self.v;
   }

   friend ostream & operator << (ostream & os, _Node const & self) {
      return os << self.v;
   }
};
// endregion


struct Algo {


int N;
ull M;
vec<ll> A;


void main() {
	cin >> N >> M;
	A.resize(N);
	cii(A, N);

	ll max_res = LONG_LONG_MIN;

	for (int h = 0; h <= N * 59; h += 1) {
		for (const auto [res, mx] : interesting_pairs(N, h)) {
			max_res = maxi(max_res, res);
		}
	}

	cout << max_res;
}


set<pair<ll, ull>> interesting_pairs(int n, int h) {
	const ll a = A[n-1];

	if (h > n * 59) { return {{}}; }

	if (n == 1) {
		ll n_res = h * a;
		ull n_mx = (1uLL << h)-1;
		if (n_mx > M) {
			return {{}};
		}
		DBG(n, h, n_res, n_mx);
		return {{n_res, n_mx}};
	}

	set<pair<ll, ull>> pairs_acc;
	for (int hb = 1; hb <= h && hb <= 59; hb += 1) {
		set<pair<ll, ull>> pairs = interesting_pairs(n-1, h - hb);
		for (const auto [res, mx] : pairs) {
			ll n_res = res + hb * a;
			ull n_mx = next_mx(mx, hb);
			if (n_mx > M) {
				continue;
			}

			DBG(n, h, hb, res, mx, n_res, n_mx);

			const auto it = pairs_acc.lower_bound({n_res, 0});
			if (it == pairs_acc.end()) {
				pairs_acc.emplace_hint(it, n_res, n_mx);
			} else if (it->second > n_mx) {
				pairs_acc.emplace_hint(it, n_res, n_mx);
				if (it->first == n_res) {
					pairs_acc.erase(it);
				}
			}
		}
	}

	return pairs_acc;
}


ull next_mx(ull mx, int hb) {
	ull n_mx = 0;
	ull h_m = 1uLL << (hb - 1);
	for (ull b = 1uLL << 59; b > 0; b >>= 1) {
		if (mx & b) {
			if (h_m & 1) {
				for (int b2 = b << 1;; b2 <<= 1) {
					if ((n_mx & b2) == 0) {
						n_mx |= b2;
						return n_mx;
					}
				}
			}
			h_m >>= 1;
			n_mx |= b;
		}
	}
	for (ull b = 1uLL;; b <<= 1) {
		if ((n_mx & b) == 0) {
			n_mx |= b;
			if (h_m & 1) {
				return n_mx;
			}
			h_m >>= 1;
		}
	}
}


};


int main() {
	MAGIC;
	Algo().main();
}