/* -*- coding: utf-8 -*-
 *
 * 1522.cc:  No.1522 Unfairness - yukicoder
 */

#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<cmath>
#include<iostream>
#include<string>
#include<vector>
#include<map>
#include<set>
#include<stack>
#include<list>
#include<queue>
#include<deque>
#include<algorithm>
#include<numeric>
#include<utility>
#include<complex>
#include<functional>
 
using namespace std;

/* constant */

const int MAX_N = 3000;
const int MAX_M = 3000;

/* typedef */

/* global variables */

int as[MAX_N], dp[MAX_N + 1][MAX_M + 1];

/* subroutines */

inline void setmax(int &a, int b) { if (a < b) a = b; }

/* main */

int main() {
  int n, m;
  scanf("%d%d", &n, &m);

  for (int i = 0; i < n; i++) scanf("%d", as + i);
  sort(as, as + n, greater<int>());

  memset(dp, -1, sizeof(dp));
  dp[0][0] = 0;

  for (int i = 0; i < n; i++) {
    int di = (i + 1 < n) ? as[i] - as[i + 1] : 0;
    for (int j = 0; j <= m; j++)
      if (dp[i][j] >= 0) {
	setmax(dp[i + 1][j], dp[i][j]);
	if (i + 1 < n)
	  setmax(dp[i + 2][j + di], dp[i][j] + as[i]);
      }
  }

  int maxd = 0;
  for (int j = 0; j <= m; j++) setmax(maxd, dp[n][j]);

  printf("%d\n", maxd);
  return 0;
}