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 = sorted(list(zip([[2,5,5,4,5,6,3,7,6][a-1] for a in A],A)),key = lambda x: (x[0],-x[1]))

#同じ画数の数字を除く
tmp = len(cost)
i = 1
while i < tmp:
    if cost[i][0] == cost[i-1][0]:
        cost.pop(i)
        tmp = len(cost)
    else:
        i += 1

stack = [[0]*(len(cost))]
while stack:
    ans_list = stack.pop()
    tmp = sum([n*cost[i][0] for i,n in enumerate(ans_list)])
    if tmp == N:
        break
    elif tmp < N:
        tmp2 = len(ans_list)
        for i in range(tmp2-1,-1,-1):
            stack.append([a + (i == j) for j,a in enumerate(ans_list)])

ans_out = sorted(list(zip(cost,ans_list)),key = lambda x: -x[0][1])

out_str = ""
for out in ans_out:
    out_str += str(out[0][1])*out[1]
print(out_str)