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)

inf = 1 << 20
need = -1, 2, 5, 5, 4, 5, 6, 3, 7, 6

n, m = map(int, input().split())
a = map(int, input().split())
d = {need[x]: x for x in sorted(a)}  # sortedで昇順にすることで、同じ本数のとき最大値が残る
e = tuple(sorted(d.items(), key=lambda x: x[1], reverse=True))  # (必要本数,数字)

dp = [-inf] * (n + 1)
dp[0] = 0
# dp[k]:=k本で構成可能な最大桁数

for j in range(1, n + 1):
    dp[j] = max((dp[j - cnt] for cnt, _ in e if j - cnt >= 0), default=-inf) + 1

ret = []
r = dp[n]

curr = n
while r > 0:
    for cnt, num in e:
        if curr - cnt >= 0 and dp[curr - cnt] == r - 1:
            ret.append(num)
            r -= 1
            curr -= cnt
            break

ret.sort(reverse=True)
print(''.join(map(str, ret)))