#include <bits/stdc++.h>
#include <unistd.h>
using namespace std;

using ll = long long;
using ld = long double;
using ull = long long;
#define endl "\n"
#define REP3(i, m, n) for (int i = (m); (i) < int(n); ++ (i))
#define rep(i,a,b) for(int i=(int)(a);i<(int)(b);i++)
#define ALL(x) begin(x), end(x)
#define all(s) (s).begin(),(s).end()
//#define rep2(i, m, n) for (int i = (m); i < (n); ++i)
//#define rep(i, n) rep2(i, 0, n)
#define drep2(i, m, n) for (int i = (m)-1; i >= (n); --i)
#define drep(i, n) drep2(i, n, 0)
#define rever(vec) reverse(vec.begin(), vec.end())
#define sor(vec) sort(vec.begin(), vec.end())
#define fi first
#define se second
#define pb push_back
#define P pair<ll,ll>
#define REP(i, n) for (int i = 0; i < (n); ++i)
#define in scanner.read_int()
//const ll mod = 998244353;
const ll mod = 1000000007;
const ll inf = 4500000000000000000ll;
static const long double pi = 3.141592653589793;
template<class T>void vcin(vector<T> &n){for(int i=0;i<int(n.size());i++) cin>>n[i];}
template<class T,class K>void vcin(vector<T> &n,vector<K> &m){for(int i=0;i<int(n.size());i++) cin>>n[i]>>m[i];}
template<class T>void vcout(vector<T> &n){for(int i=0;i<int(n.size());i++){cout<<n[i]<<" ";}cout<<endl;}
template<class T>void vcin(vector<vector<T>> &n){for(int i=0;i<int(n.size());i++){for(int j=0;j<int(n[i].size());j++){cin>>n[i][j];}}}
template<class T>void vcout(vector<vector<T>> &n){for(int i=0;i<int(n.size());i++){for(int j=0;j<int(n[i].size());j++){cout<<n[i][j]<<" ";}cout<<endl;}cout<<endl;}
void yes(bool a){cout<<(a?"yes":"no")<<endl;}
void YES(bool a){cout<<(a?"YES":"NO")<<endl;}
void Yes(bool a){cout<<(a?"Yes":"No")<<endl;}
void possible(bool a){ cout<<(a?"possible":"impossible")<<endl; }
void Possible(bool a){ cout<<(a?"Possible":"Impossible")<<endl; }
void POSSIBLE(bool a){ cout<<(a?"POSSIBLE":"IMPOSSIBLE")<<endl; }template<class T>bool chmax(T &a, const T &b) { if (a<b) { a=b; return 1; } return 0;}

void cincout(){
  ios::sync_with_stdio(false);
    std::cin.tie(nullptr);
  cout<< fixed << setprecision(20);
}

int main() {
  cincout();
  ll a,b;
  cin>>a>>b;
  vector<ll> x(a-1);
  vector<ll> y(a-1);
  vector<ll> t(a);
  vcin(t);
  sor(t);
  for(int i=0;i<a-1;i++){
    y[i]=t[i+1];
    x[i]=t[i+1]-t[i];
    swap(x[i],y[i]);
  
  }
  a--;
  //x価値 y重さ
  vector<vector<ll>> dp(7000,vector<ll>(7000,-inf));
  rever(x);
  rever(y);
  dp[0][0]=0;
  for(int i=0;i<a;i++){
    if(1){
      for(int j=0;j<=6999;j++) chmax(dp[i+1][j],dp[i][j]);
    }
    if(1){
    for(int j=0;j<=6999;j++){
      if(j-y[i]>=0) chmax(dp[i+2][j],dp[i][j-y[i]]+x[i]);
      chmax(dp[i+2][j],dp[i][j]);
    }
    }
    for(int j=1;j<=6999;j++) chmax(dp[i][j],dp[i][j-1]);
  }
  cout<<dp[a-1][b]<<endl;
}