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 Python (3.4.3) (judge verdict: Runtime Error)

from collections import defaultdict
N,M,*A = map(int, open(0).read().split())
ls = [0]*10
ls[1] = 2
ls[2] = 5
ls[3] = 5
ls[4] = 4
ls[5] = 5
ls[6] = 6
ls[7] = 3
ls[8] = 7
ls[9] = 6
dic = defaultdict(int)
for a in A:
  k = ls[a]
  dic[k] = max(dic[k],a)
dp = [-1]*(N+1)
for k in dic.keys():
  dp[k] = dic[k]
for i in range(N+1):
  for k in dic.keys():
    if i-k>0 and dp[i-k]!=-1:
      s = str(dp[i-k])
      m = int(str(dic[k])+s)
      dp[i] = max(dp[i], m)
print(dp[N])