#include <algorithm>
#include <cmath>
#include <iomanip>
#include <iostream>
#include <map>
#include <queue>
#include <set>
#include <string>
#include <tuple>
#include <vector>

#define mkp make_pair
#define mkt make_tuple
#define rep(i, n) for (int i = 0; i < (n); ++i)
#define all(v) v.begin(), v.end()
using namespace std;
typedef long long ll;
const ll MOD = 1e9 + 7;
// const ll MOD = 998244353;
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;
}

const ll INF = 1e18;

void solve() {
    int N, M;
    cin >> N >> M;
    vector<ll> A(N);
    rep(i, N) cin >> A[i];

    sort(all(A));
    reverse(all(A));

    vector<vector<ll>> dp(N + 1, vector<ll>(M + 1, -INF));
    dp[0][0] = 0;
    for (int i = 0; i < N; i++) {
        for (int j = 0; j <= M; j++) {
            ll value = dp[i][j];
            if (value == -INF) continue;
            chmax(dp[i + 1][j], value);
            if (i + 2 <= N && j + A[i] - A[i + 1] <= M)
                chmax(dp[i + 2][j + A[i] - A[i + 1]], value + A[i]);
        }
    }

    ll ans = *max_element(all(dp[N]));
    cout << ans << endl;
}

int main() {
    cin.tie(nullptr);
    ios::sync_with_stdio(false);

    solve();

    return 0;
}