#include <cassert>
#include <cmath>
#include <algorithm>
#include <iostream>
#include <iomanip>
#include <climits>
#include <map>
#include <queue>
#include <set>
#include <cstring>
#include <vector>

using namespace std;
typedef long long ll;

int main() {
  int N, M;
  cin >> N >> M;

  vector<int> A(N);
  for (int i = 0; i < N; ++i) {
    cin >> A[i];
  }

  sort(A.begin(), A.end());
  reverse(A.begin(), A.end());

  ll dp[N][M + 1];
  memset(dp, -1, sizeof(dp));
  dp[0][0] = 0;
  dp[1][A[0] - A[1]] = A[0];

  for (int i = 1; i < N; ++i) {
    for (int j = 0; j <= M; ++j) {
      dp[i][j] = max(dp[i][j], dp[i - 1][j]);

      if (i - 2 >= 0) {
        int ba = j - (A[i - 1] - A[i]);
        if (ba >= 0 && dp[i - 2][ba] >= 0) {
          dp[i][j] = max(dp[i][j], dp[i - 2][ba] + A[i - 1]);
        }
      }
    }

    /*
    for (int j = 0; j <= M; ++j) {
      cerr << dp[i][j] << " ";
    }
    cerr << endl;
    */
  }

  ll ans = 0;

  for (int m = 0; m <= M; ++m) {
    ans = max(ans, dp[N - 1][m]);
  }

  cout << ans << endl;

  return 0;
}