#include <iostream>
#include <string>
#include <algorithm>
#include <vector>
#include <iomanip>
#include <cmath>
#include <stdio.h>
#include <queue>
#include <deque>
#include <cstdio>
#include <set>
#include <map>
#include <bitset>
#include <stack>
#include <cctype>
using namespace std;
long dp[3030][3030] = {};
long a[3030], r[3030];
int main() {
	long n, m;
	cin >> n >> m;
	for (long i = 1; i <= n; i++) {
		cin >> r[i];
	}
	sort(r + 1, r + n + 1);
	for (int i = 1; i <= n; i++) {
		a[i] = r[n - i + 1];
	}
	for (int i = 1; i < n; i++) {
		for (int j = 0; j <= m; j++) {
			dp[i + 1][j] = max(dp[i + 1][j], dp[i][j]);
			if (a[i] - a[i + 1] <= m - j) {
				dp[i + 2][j + a[i] - a[i + 1]] = max(dp[i + 2][j + a[i] - a[i + 1]], dp[i][j] + a[i]);
			}
			if (i != n - 1 && a[i] - a[i + 2] <= m - j) {
				dp[i + 3][j + a[i] - a[i + 2]] = max(dp[i + 3][j + a[i] - a[i + 2]], dp[i][j] + a[i]);
			}
		}
	}
	long ans = 0;
	for (int i = 1; i <= n + 1; i++) {
		for (int j = 0; j <= m; j++) {
			ans = max(ans, dp[i][j]);
		}
	}
	cout << ans << endl;
}