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: Accepted)

N,M=map(int,input().split())
*A,=map(int,input().split())

# 0初期化ではダメ。組合せ不可を表し、演算しても問題ない状態にしておく
dp=[-float("inf")] * (N+1)
dp[0]=0

cost =[0, 2,5,5,4,5,6,3,7,6]
for i in range(N+1):
    for a in A:
      # -inf初期化なので、不可能なものの演算結果も同じ
       new_i = i + cost[a]
       if new_i <= N:
        dp[new_i] = max([dp[new_i],  dp[i]+1])

sa = sorted(A, reverse=True)
n = N
ans = 0
while n > 0:
  for a in sa:
    nn = n-cost[a]
    if nn >= 0 and dp[n] == dp[nn] +1:
      ans = ans * 10 + a
      n -= cost[a]
      break

print(ans)