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: N, M = list(map(int, input().split()))
  
  A = list(map(int, input().split())) #len(A)=M
  
  _dict={}
  num_matches={1:2,2:5,3:5,4:4,5:5,6:6,7:3,8:7,9:6}
  
  for a in A:
    _dict[num_matches[a]]=_dict.get(num_matches[a],[]) + [a]
  
  print(_dict)
  
  memo = [None for _ in range(N+1)] # return memo[N]
  # Nほんのマッチを使って作れる整数の最大値．（作れなければ0）
  
  def max_int_with_match(n):
    if memo[n]:
      return memo[n]
    
    if n in _dict.keys():
      memo[n] = max(max(_dict[n]),
                    max(map(lambda x: max(_dict[x]) + 10 * max_int_with_match(n-x), _dict.keys()
                           )
                       )
                   )
    	return memo[n]
    
    if n < min(_dict.keys()):
      memo[n] = 0
      return memo[n]
    
    memo[n] = max(map(lambda x: max(_dict[x]) + 10 * max_int_with_match(n-x), _dict.keys()))
    return memo[n]
  
  print(max_int_with_match(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"}]