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

#ifdef _DEBUG
#include "_DEBUG.hpp"
#endif
#define int long long
const long long inf = 2e18;
const int mod = 1e9 + 7;

template <typename T>
istream &operator>>(istream &is, vector<T> &v) {
  for (T &in : v) is >> in;
  return is;
}

template <class T>
vector<T> make_vec(size_t a) {
  return vector<T>(a);
}

template <class T, class... Ts>
auto make_vec(size_t a, Ts... ts) {
  return vector<decltype(make_vec<T>(ts...))>(a, make_vec<T>(ts...));
}

template <class T, class V>
typename enable_if<is_class<T>::value == 0>::type fill(T &t, const V &v) {
  t = v;
}

template <class T, class V>
typename enable_if<is_class<T>::value != 0>::type fill(T &t, const V &v) {
  for (auto &e : t) fill(e, v);
}

signed main() {
  int n, m;
  cin >> n >> m;
  vector<int> a(n);
  cin >> a;

  sort(a.rbegin(), a.rend());

  auto dp = make_vec<int>(n + 1, m + 1);
  fill(dp, -inf);
  dp[0][0] = 0;
  for (int i = 0; i < n; i++) {
    for (int j = 0; j <= m; j++) {
      if (i + 2 <= n && j + a[i] - a[i + 1] <= m)
        dp[i + 2][j + a[i] - a[i + 1]] =
            max(dp[i + 2][j + a[i] - a[i + 1]], dp[i][j] + a[i]);
      dp[i + 1][j] = max(dp[i + 1][j], dp[i][j]);
    }
  }
  int ans = *max_element(dp[n].begin(), dp[n].end());
  cout << ans << endl;

  return 0;
}