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)

def main():
    N, M = map(int, input().split())

    A = list(map(int, input().split()))  # 使っていい数字

    match_dic = {9: 6, 8: 7, 7: 3, 6: 6, 5: 5, 4: 4, 3: 5, 2: 5, 1: 2}
    available_dic = {k: v for k, v in match_dic.items() if k in A }
    availables = sorted(available_dic.items(), key=lambda x: x[1])

    def dfs(cost, nums):
        if cost == 0:
            nums.sort(key=lambda x: -x)
            return int(''.join(map(str, nums)))

        candidates = [dfs(cost - avs[1], nums + [avs[0]]) for avs in availables if cost >= avs[1]]
        if len(candidates) == 0:
            return 0
        else:
            return max(candidates)

    print(dfs(N, []))


main()