#include <iostream>
#include <algorithm>
#include <vector>

using namespace std;
constexpr int INF = 1 << 30;

void solve() {
    int n, m;
    cin >> n >> m;

    vector<int> xs(n);
    for (auto& x : xs) cin >> x;
    sort(xs.begin(), xs.end());

    auto dp = vector(n + 1, vector(m + 1, -INF));
    dp[0][0] = 0;

    for (int i = 0; i < n; ++i) {
        for (int j = 0; j <= m; ++j) {
            dp[i + 1][j] = max(dp[i + 1][j], dp[i][j]);
        }

        if (i + 1 >= n) continue;

        auto x = xs[i + 1];
        auto d = xs[i + 1] - xs[i];
        for (int j = 0; j + d <= m; ++j) {
            dp[i + 2][j + d] = max(dp[i + 2][j + d], dp[i][j] + x);
        }
    }

    cout << *max_element(dp[n].begin(), dp[n].end()) << "\n";
}

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

    solve();

    return 0;
}