Go: ///
// File:  0529.go
// Author: ymiyamoto
//
// Created on Wed Feb 28 20:39:28 2018
//
package main

import (
	"fmt"
	"sort"
)

func max(n, m int) int {
	if n < m {
		return m
	} else {
		return n
	}
}

func main() {
	for {
		var N, M int
		fmt.Scan(&N, &M)
		if N == 0 && M == 0 {
			break
		}

		arr := make([]int, N+1)
		for i := 1; i <= N; i++ {
			fmt.Scan(&arr[i])
		}
		sort.Ints(arr)

		sums := make([]int, len(arr)*len(arr))
		for i := 0; i < len(arr); i++ {
			for j := 0; j < len(arr); j++ {
				sums[i+j] = arr[i] + arr[j]
			}
		}
		sort.Ints(sums)

		m := 0
		for i := 0; i < len(sums); i++ {
			rem := M - sums[i]
			if rem >= 0 {
				index := sort.Search(len(sums), func(i int) bool { return sums[i] > rem }) - 1
				if index >= 0 {
					m = max(m, sums[i]+sums[index])
				}
			}
		}
		fmt.Println(m)
	}
}

C++: #include <cstdio>
#include <cctype>
#include <utility>
#include <vector>
#include <algorithm>
using namespace std;

const auto gcu = getchar_unlocked;
const auto pcu = putchar_unlocked;
#define _T template <typename T>
#define _HT template <typename H, typename... T>
#define _il inline
#define _sc _il bool scan
_T T in(int c){T n=0;int m=1;while(isspace(c)){c=gcu();}if(c=='-')m=-1,c=gcu();
	do{n=10*n+(c-'0'),c=gcu();}while(c>='0'&&c<='9');return m*n;}
_il int in() {return in<int>(gcu());}
_T T scan(T &n){int c=gcu();return c==EOF?false:(n=in<T>(c),true);}
_sc(char &c){c=gcu();gcu();return c!=EOF;}
#ifdef _GLIBCXX_STRING
_sc(string &s){int c;s="";
	for(;;){c=gcu();if(c=='\n'||c==' ')return true;else if(c==EOF)return false;s+=c;}}
#endif
_HT _sc(H &h, T&&... t){return scan(h)&&scan(t...);}
#define _ot _il void out
#define _ol _il void outl
_ot(bool b) {pcu('0'+b);}
_ot(const char *s){while(*s)pcu(*s++);}
_ot(char c){pcu(c);}
#ifdef _GLIBCXX_STRING
_ot(string s){for(char c:s)pcu(c);}
#endif
_T _ot(T n){static char b[20];char *p=b,m=n<0?pcu('-'),-1:1;
	if(!n)*p++='0';else while(n)*p++=n%10*m+'0',n/=10;while(p!=b)pcu(*--p);}
_ol(){out('\n');}
#ifdef _GLIBCXX_VECTOR
_T _ot(vector<T> &v){for(T &x:v)out(&x == &v[0]?"":" "),out(x);outl();}
#endif
_HT _ot(H&& h, T&&... t){out(h);out(move(t)...);}
template <typename... T> _ol(T&&... t){out(move(t)...);outl();}

int main() {
	for (int N, M; N = in(), M = in();) {
		vector<int> t(N), u;
		for (int &p: t)
			p = in();
		t.push_back(0);
		sort(t.begin(), t.end());
		for (auto i = t.begin(); i != t.end(); i++)
			for (auto j = i; j != t.end(); j++)
				if (*i + *j <= M)
					u.push_back(*i + *j);
		sort(u.begin(), u.end());
		u.erase(unique(u.begin(), u.end()), u.end());
		int r = 0;
		for (auto i = u.begin(), e = u.end() - 1; i <= e; i++) {
			for (; *i + *e >= M; e--)
				;
			if (*i + *e > r)
				r = *i + *e;
		}
		outl(r);
	}
}

C++: #include <algorithm>
#include <cmath>
#include <climits>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <fstream>
#include <iostream>
#include <list>
#include <map>
#include <queue>
#include <set>
#include <sstream>
#include <stack>
#include <string>
#include <vector>
#include <cassert>
#include <functional>

using namespace std;

#define LOG(...) printf(__VA_ARGS__)
//#define LOG(...)
#define FOR(i,a,b) for(int i=(int)(a);i<(int)(b);++i)
#define REP(i,n) for(int i=0;i<(int)(n);++i)
#define ALL(a) (a).begin(),(a).end()
#define RALL(a) (a).rbegin(),(a).rend()
#define EXIST(s,e) ((s).find(e)!=(s).end())
#define SORT(c) sort((c).begin(),(c).end())
#define RSORT(c) sort((c).rbegin(),(c).rend())
#define CLR(a) memset((a), 0 ,sizeof(a))

typedef long long ll;
typedef unsigned long long ull;
typedef vector<bool> vb;
typedef vector<int> vi;
typedef vector<ll> vll;
typedef vector<vb> vvb;
typedef vector<vi> vvi;
typedef vector<vll> vvll;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;

const int dx[] = { -1, 0, 1, 0 }; const int dy[] = { 0, 1, 0, -1 };

int main() {
	int n, m;
	while (cin >> n >> m, n){
		vector<int> point(n);
		REP(i, n){
			cin >> point[i];
		}
		point.push_back(0);
		vector<int> sum = point;
		REP(i, n + 1){
			REP(j, n + 1){
				if (count(sum.begin(), sum.end(), sum[i] + sum[j]) == 0)
					sum.push_back(sum[i] + sum[j]);
			}
		}
		SORT(sum);
		int ma = 0;
		REP(i, sum.size()){
			int left = 0;
			int right = sum.size() - 1;
			while (left < right){
				if (sum[left + (right - left) / 2] + sum[i] <= m){
					ma = max(sum[left + (right - left) / 2] + sum[i], ma);
					left = left + (right - left) / 2 + 1;

				}
				else{
					right = left + (right - left) / 2 - 1;
				}
			}
			
		}
		cout << ma << endl;
	}
}

C++: #include<iostream>

#define NMAX 1000
#define MMAX 200000000
using namespace std;

int main(void){

	std::ios_base::sync_with_stdio();

	int N,M;
	int max=-1;
	int dp[4][MMAX]={-1};
	int sc[NMAX];

	while(1){
		cin>>N>>M;
		if(N==0&&M==0) break;
		for(int i=0;i<N;i++){
			cin>>sc[i];
		}
		for(int i=0;i<4;i++){
			for(int j=0;j<MMAX;j++){
				dp[i][j]=-1;
			}
		}
		dp[0][0]=1;
		for(int j=0;j<=M;j++){
			for(int k=0;k<4;k++){
				if(dp[k][j]==1){
					for(int l=0;l<N;l++){
						if(j+sc[l]<=M){
							dp[k+1][j+sc[l]]=1;
							if(max<j+sc[l]) max=j+sc[l];
						}
					}
				}
			}
		}
		cout<<max<<endl;
	}


	return 0;
}

C++: #include "stdio.h"
#include <iostream>
#include <algorithm>

using namespace std;

long long int gten[1111111];
long long int p[1111];

long long int ans[1000];

int main()
{
  int ww = 0;
  while(1)
    {
      long long int n,m;
      scanf("%lld %lld",&n,&m);
      if(n == 0 && m == 0)
	{
	  break;
	}
      p[0] = 0;
      for(int i = 1; i <= n; i++)
	{
	  scanf("%lld",&(p[i]));
	}
      int nw = 0;
      for(int i = 0; i <= n; i++)
	{
	  for(int ii = 0; ii <= n; ii++)
	    {
	      gten[nw] = p[i] + p[ii];
	      nw++;
	    }
	}
      sort(gten,gten + nw);
      long long int max = 0;
      int ai = 0;
      for(int i = nw - 1; i >= 0; i--)
	{
	  while(1)
	    {
	      if(ai + 1 >= nw)
		{
		  break;
		}
	      if(gten[i] + gten[ai + 1] <= m)
		{
		  ai++;
		  if(max < gten[i] + gten[ai])
		    {
		      max = gten[i] + gten[ai];
		    }
		}
	      else
		{
		  break;
		}
	    }
	}
      ans[ww] = max;
      ww++;
    }
  for(int i = 0; i < ww; i++)
    {
      printf("%lld\n",ans[i]);
    }
  return 0;
}

C++: #include<iostream>
#include<vector>
#include<algorithm>
using namespace std;

int main(){
while(1){
	int n,m,a,ans=0;
	vector<int> p,pp;
	scanf("%d%d",&n,&m);
	p.push_back(0);
	for(int i=0;i<n;i++){
		scanf("%d",&a);
		p.push_back(a);
	}
	for(int i=0;i<=n;i++){
		for(int j=i;j<=n;j++){
			pp.push_back(p[i]+p[j]);
		}
	}
	sort(pp.begin(),pp.end());
	int s=pp.size()-1;
	for(int i=0;i<=s;i++){
		while(pp[i]+pp[s]>m)s--;
		if(ans<pp[i]+pp[s])ans=pp[i]+pp[s];
	}
	printf("%d\n",ans);
}
}

C++: #include <iostream>
#include <algorithm>
#include <vector>
using namespace std;

const long long INF = 200000000;
int N;
long long M;
vector<long long> target;

int main(void) {
	while (cin >> N >> M, M) {
		// input
		target.clear(); target.resize(N + 1);
		for (int i = 0; i < N; i++) {
			cin >> target[i];
		}
		target.push_back(0);

		// calc
		vector<long long> ab;
		ab.reserve((N + 1) * (N + 1));
		for (int i = 0; i <= N; i++) {
			for (int j = 0; j <= N; j++) {
				ab.push_back(target[i] + target[j]);
			}
		}

		sort(ab.begin(), ab.end());

		long long res = 0;
		for (int i = 0; i < ab.size(); i++) {
			if (ab[i] > M) {
				break;
			}
			vector<long long>::iterator it = upper_bound(ab.begin(), ab.end(), M - ab[i]);
			res = max(res, ab[i] + *(it - 1));
		}
		
		// output
		cout << res << endl;
	}

	return 0;
}