#include <bits/stdc++.h>
#pragma GCC optimize("Ofast")
#define _GLIBCXX_DEBUG
using namespace std;
using std::cout;
using std::cin;
using std::endl;
using ll=long long;
using ld=long double;
ll ILL=1167167167167167167;
const int INF=2100000000;
const ll mod=1e9+7;
#define rep(i,a) for (int i=0;i<a;i++)
template<class T> using _pq = priority_queue<T, vector<T>, greater<T>>;
template<class T> ll LB(vector<T> &v,T a){return lower_bound(v.begin(),v.end(),a)-v.begin();}
template<class T> ll UB(vector<T> &v,T a){return upper_bound(v.begin(),v.end(),a)-v.begin();}
template<class T> bool chmin(T &a,const T &b){if(a>b){a=b;return 1;}else return 0;}
template<class T> bool chmax(T &a,const T &b){if(a<b){a=b;return 1;}else return 0;}
template<class T> void So(vector<T> &v) {sort(v.begin(),v.end());}
template<class T> void Sore(vector<T> &v) {sort(v.begin(),v.end(),[](T x,T y){return x>y;});}
void yneos(bool a){if(a) cout<<"YES\n"; else cout<<"NO\n";}



void solve();
// oddloop
int main() {
	ios::sync_with_stdio(false);
	cin.tie(nullptr);
	
	int t=1;
	//cin>>t;
	rep(i,t) solve();
}

void solve(){
	int N,M;
	cin>>N>>M;
	vector<int> A(N);
	rep(i,N) cin>>A[i];
	vector<vector<int>> dp(N+1,vector<int>(M+1,-INF));
	So(A);
	dp[0][0]=0;
	rep(i,N){
		rep(j,M+1){
			if(dp[i][j]==-INF) continue;
			chmax(dp[i+1][j],dp[i][j]);
			if(i==N-1) continue;
			int tmp=j+A[i+1]-A[i];
			if(tmp<=M) chmax(dp[i+2][tmp],dp[i][j]+A[i+1]);
		}
	}
	int ans=0;
	rep(j,M+1) chmax(ans,dp[N][j]);
	cout<<ans<<"\n";
}