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 Ruby (2.3.3) (judge verdict: Time Limit Exceeded)

n, m = gets.chomp.split(' ').map(&:to_i)
as = gets.chomp.split(' ').map(&:to_i).sort.reverse

#          1, 2, 3, 4, 5, 6, 7, 8, 9
COST = [0, 2, 5, 5, 4, 5, 6, 3, 7, 6]

def find_min_cost(list, costs)
  num = 0
  min_cost = 10
  list.reverse.each do |i|
    cost = costs[i]
    if cost <= min_cost
      num = i
      min_cost = cost
    end
  end
  [num, min_cost]
end

def find_max_num(rest, cost_hash)
  cost_hash.each do |num, cost|
    if cost <= rest
      return [num, rest - cost]
    end
  end
  [nil, rest]
end

min_cost_num, min_cost = find_min_cost(as, COST)
chars = Array.new(n / min_cost) { min_cost_num.to_s }
rest = n % min_cost

if rest > 0
  active_costs = as.map { |i| [i, COST[i]] }.to_h

  while rest > 0
    i = chars.shift
    rest += COST[i.to_i]
    num, rest = find_max_num(rest, active_costs)
    chars << num.to_s unless num.nil?
  end
end

puts chars.sort.reverse.join