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

using namespace std;
using ll = long long;
using ull = unsigned long long;
#define rep(i,n) for(int i=0; i<(n); i++)

const ll INF = 1001001001001001001;

ll dp[3001][3001] = {};


int main(){
  int N, M; cin >> N >> M;
  vector<ll> A(N);
  rep(i,N) cin >> A[i];
  sort(A.begin(),A.end());

  rep(i,3001) rep(j,3001) dp[i][j] = -INF;
  rep(s,3001) dp[0][s] = 0;
  rep(i,N+1) rep(s,M+1){
    if(i >= 1) dp[i][s] = max(dp[i][s], dp[i-1][s]);
    if(i >= 2) if(A[i-1]-A[i-2] <= s) dp[i][s] = max(dp[i][s], dp[i-2][s - (A[i-1]-A[i-2])] + A[i-1]);
  }

  cout << dp[N][M] << "\n";
  return 0;
}


struct ios_do_not_sync{
  ios_do_not_sync(){
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
  }
} ios_do_not_sync_instance;