#include <stdio.h>
#include <bits/stdc++.h>
#include <atcoder/all>
using namespace atcoder;
using mint = modint1000000007;
using namespace std;
#define rep(i,n) for (int i = 0; i < (n); ++i)
#define Inf 1000000001

int main(){
	
	int N,M;
	cin>>N>>M;
	
	vector<long long> A(N);
	rep(i,N)cin>>A[i];
	
	sort(A.rbegin(),A.rend());
	
	vector<vector<long long>> dp(N+1,vector<long long>(M+1,0));
	
	rep(i,N){
		rep(j,M+1){
			dp[i+1][j] = max(dp[i+1][j],dp[i][j]);
			if(i==N-1)continue;
			int X = A[i] - A[i+1];
			if(j+X>M)break;
			dp[i+2][j+X] = max(dp[i+2][j+X],dp[i][j] + A[i]);
		}
	}
	
	long long ans =0 ;
	rep(i,M+1)ans = max(ans,dp.back()[i]);
	
	cout<<ans<<endl;
	
	return 0;
}