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: Wrong Answer)

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

namespace AtCoder
{
	public class ABC
	{
		static int mod = 1000000007;  // 10^9+7

		static int[] match = { 6, 2, 5, 5, 4, 5, 6, 3, 7, 6 };
		static int[] a;
		static StringBuilder sb = new StringBuilder();

		static void Main(string[] args)
		{
			Console.SetOut(new StreamWriter(Console.OpenStandardOutput()) { AutoFlush = false });


			//int n = int.Parse(Console.ReadLine());
			//string s = Console.ReadLine();
			int[] vs = Console.ReadLine().Split().Select(int.Parse).ToArray();
			int n = vs[0];
			int m = vs[1];
			a = Console.ReadLine().Split().Select(int.Parse).ToArray();
			Array.Sort(a, (x, y) => {
				int result = match[x].CompareTo(match[y]);
				if (result == 0) {
					result = -x.CompareTo(y);
				}
				return result;
			});

			//System.Diagnostics.Debug.WriteLine(string.Join(" ", a));
			//foreach (var item in a) {
			//	System.Diagnostics.Debug.Write($"{match[item]} ");
			//}
			//System.Diagnostics.Debug.WriteLine("");

			dfs(n);
			string ans = string.Join("", sb.ToString().OrderByDescending(p => p));
			Console.WriteLine(ans);


			Console.Out.Flush();
		}

		static bool dfs(int n)
		{
			for (int i = 0; i < a.Length; i++) {
				int c = n - match[a[i]];
				if (c == 0) {
					sb.Append(a[i]);
					return true;
				} else if (c < 0) {
					return false;
				} else {
					bool result = dfs(c);
					if (result) {
						sb.Append(a[i]);
						return true;
					}
				}
			}
			return false;
		}

	}
}