Problem:
Score : 400 points

Problem Statement

Find the largest integer that can be formed with exactly N matchsticks, under the following conditions:

Every digit in the integer must be one of the digits A_1, A_2, ..., A_M (1 \leq A_i \leq 9).

The number of matchsticks used to form digits 1, 2, 3, 4, 5, 6, 7, 8, 9 should be 2, 5, 5, 4, 5, 6, 3, 7, 6, respectively.

Constraints

All values in input are integers.

2 \leq N \leq 10^4

1 \leq M \leq 9

1 \leq A_i \leq 9

A_i are all different.

There exists an integer that can be formed by exactly N matchsticks under the conditions.

Input

Input is given from Standard Input in the following format:

N M
A_1 A_2 ... A_M

Output

Print the largest integer that can be formed with exactly N matchsticks under the conditions in the problem statement.

Sample Input 1

20 4
3 7 8 4

Sample Output 1

777773

The integer 777773 can be formed with 3 + 3 + 3 + 3 + 3 + 5 = 20 matchsticks, and this is the largest integer that can be formed by 20 matchsticks under the conditions.

Sample Input 2

101 9
9 8 7 6 5 4 3 2 1

Sample Output 2

71111111111111111111111111111111111111111111111111

The output may not fit into a 64-bit integer type.

Sample Input 3

15 3
5 4 6

Sample Output 3

654

Solution in C# (Mono 4.6.2.0) (judge verdict: Accepted)

using System;
using System.Collections.Generic;
using System.Linq;

namespace ABC118D
{
    class MainClass
    {
        static int[] s;
        static int[] a;
        static string[] dp;
        static int[] w = new int[10] { 0, 2, 5, 5, 4, 5, 6, 3, 7, 6 };

        public static void Main(string[] args)
        {

            s = Array.ConvertAll(Console.ReadLine().Split().ToArray(), int.Parse);
            a = Array.ConvertAll(Console.ReadLine().Split().ToArray(), int.Parse);

            Array.Sort(a, delegate (int x, int y)
            {
                return w[x].CompareTo(w[y]);
            });

            dp = new string[s[0] + 1];


           Console.WriteLine(Dp(s[0]));
    



        }



        public static string Dp(int m)
        {
            //Console.WriteLine(m);
            if (dp[m] != null)//calcurated
            {
                return dp[m];
            }
            else
            {
                string tmp = "-1";


                string ans = "-1";
                for (int i = 0; i < a.Length; i++)
                {
                    //Console.WriteLine("now a , w , aleng, i , m: " + a[i] + " " + w[a[i]] + " " + a.Length + " " + i + " " + m);
                    if (m - w[a[i]] == 0)
                    {
                        tmp = a[i].ToString();
                        dp[m] = tmp;
                    }
                    else if (m - w[a[i]] > 0)
                    {
                        int wt = m - w[a[i]];
                        string res = Dp(wt);
                        if (res != "-1")
                        {
                            res = a[i].ToString()+res;
                            tmp = res;
                        }
                    }
                    if (tmp == "-1" && ans == "-1") {
                        ans = "-1"; 
                    }else if (tmp == "-1")
                    {
                        
                    }else if (ans == "-1")
                    {
                        ans = tmp;
                    }
                    else
                    {
                        if (ans.Length == tmp.Length)
                        {
                            if (string.Compare(ans, tmp, StringComparison.Ordinal) > 0)
                            {

                            }
                            else
                            {
                                ans = tmp;
                            }
                        }
                        else if(ans.Length>tmp.Length)
                        {

                        }
                        else
                        {
                            ans = tmp;
                        }
                    }

                }
                dp[m] = ans;
                return ans;
            }
        }
    }
}