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: Runtime Error)

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

using E = System.Linq.Enumerable;

public class Program
{
    public static void Main()
    {
        var nm = Console.ReadLine().Split().Select(x => int.Parse(x)).ToArray();
        var n = nm[0];
        var m = nm[1];
        var nums = Console.ReadLine().Split().Select(x => int.Parse(x)).ToArray();
        Array.Sort(nums);

        var needs = new [] { int.MaxValue, 2, 5, 5, 4, 5, 6, 3, 7, 6 };
        var pairNeeds = nums.SelectMany(x => nums.Select(y => needs[x] + needs[y])).ToArray();
        Array.Sort(pairNeeds);
        var repeatingDigit = nums.OrderBy(x => needs[x]).First();
        var rest = n % needs[repeatingDigit];
        while (Array.BinarySearch(pairNeeds, rest) < 0)
        {
            rest += needs[repeatingDigit];
        }
        int[] digits = null;;
        for (int i = 0; i < nums.Length; i++)
        for (int j = 0; j < nums.Length; j++)
        {
            if (needs[nums[i]] + needs[nums[j]] != rest)
            {
                continue;
            }

            digits = new int[] { repeatingDigit, nums[i], nums[j] };
            break;
        }
        Array.Sort(digits);

        for (int i = 0; i < digits.Length; i++)
        {
            var d = digits[digits.Length - i - 1];
            Console.Write(d == repeatingDigit ? new string((char)('0' + d), (n - rest) / needs[repeatingDigit]) : d.ToString());
        }
        Console.WriteLine();
    }
}