output_description: Print the largest integer that can be formed with exactly N matchsticks under
  the conditions in the problem statement.
  
  * * *
input_description: Input is given from Standard Input in the following format:
  
      
      
      N M
      A_1 A_2 ... A_M
attempt: from sys import stdin
  
  N, M = [int(x) for x in stdin.readline().rstrip().split()]
  S = [2, 5, 5, 4, 5, 6, 3, 7, 6]
  A = [int(x) for x in stdin.readline().rstrip().split()]
  B = [(x, S[x - 1]) for x in A]
  B.sort(key=lambda x: x[1])
  print(B)
  
  
  def solve(match, ans):
      if match == 0:
          return int(ans)
      if match < B[0][1]:
          return -1
      return max([solve(match - B[k][1], ans + str(B[k][0])) for k in range(len(A))])
  
  
  print(solve(N, ""))
  
problem_description: 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.
samples: [{"input": "20 4\n    3 7 8 4", "output": "777773\n    \n\nThe integer 777773 can be formed with 3 + 3 + 3 + 3 + 3 + 5 = 20 matchsticks,\nand this is the largest integer that can be formed by 20 matchsticks under the\nconditions.\n\n* * *"}, {"input": "101 9\n    9 8 7 6 5 4 3 2 1", "output": "71111111111111111111111111111111111111111111111111\n    \n\nThe output may not fit into a 64-bit integer type.\n\n* * *"}, {"input": "15 3\n    5 4 6", "output": "654"}]