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: Wrong Answer)

N, M = map(int, input().split())
A = list(map(int, input().split()))
cost = [-1, 2, 5, 5, 4, 5, 6, 3, 7, 6]
can_cost = sorted([cost[a] for a in A])
D = {}
for a in A:
    c = cost[a]
    D[c] = max(a, D.setdefault(c, -1))

min_cost = can_cost[0]
min_cost_num = D[min_cost]
K = N // min_cost
r = N - K * min_cost
temp = int("".join([str(min_cost_num)] * K))

dp = [[-1 for _ in range(min(r, K) + 1)] for __ in range(r + 1)]
dp[0][0] = temp


def f(v, l):
    L = list(str(v))
    set_L = set(L)
    cost_list = [cost[int(a)] for a in set_L]
    min_cost = min(cost_list)
    num = D.setdefault(min_cost + l, -1)
    if num == -1:
        return -1

    min_cost_num = D[min_cost]
    L[L.index(str(min_cost_num))] = str(num)
    L.sort(reverse=True)
    return int("".join(L))


for k in range(min(r, K)):
    for n in range(r):
        v = dp[n][k]
        if v == -1:
            continue
        for l in range(1, r - n + 1):
            dp[n + l][k + 1] = max(dp[n + l][k + 1], f(v, l))

print(max(dp[r]))