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

namespace ABC118_D___Match_Matching
{
    class Program
    {
        static void Main(string[] args)
        {
            var stroke = new int[] { 0, 2, 5, 5, 4, 5, 6, 3, 7, 6 };
            var NM = Array.ConvertAll(Console.ReadLine().Split(' '), int.Parse);
            var Ai = Array.ConvertAll(Console.ReadLine().Split(' '), int.Parse).OrderByDescending(n => n).ToArray();

            var matches = new Dictionary<int, int>();
            foreach (int i in Ai)
            {
                if (matches.ContainsKey(stroke[i])) continue;
                matches.Add(stroke[i], i);
            }

            var DP = new String[NM[0] + 10];
            for (int i = 0; i < DP.Length; i++) DP[i] = "";
            foreach (int i in matches.Keys) DP[i] = matches[i].ToString();
            for (int i = 0; i < NM[0]; i++)
            {
                if (DP[i] != "")
                {
                    foreach (int j in matches.Keys)
                    {
                        var temp = DP[i] + matches[j].ToString();
                        if (temp.Length > DP[i + j].Length || (temp.Length == DP[i + j].Length && temp.CompareTo(DP[i + j]) > 0)) DP[i + j] = temp;
                    }
                }
            }
            Console.WriteLine(DP[NM[0]]);
        }
    }
}