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)

n, m = map(int, input().split())
lst = list(map(int, input().split()))
lst = sorted(lst, key = lambda x:-x)
dic = {1:2, 2:5, 3:5, 4:4, 5:5, 6:6, 7:3, 8:7, 9:6}

s = set()
for i in lst:
    s.add(dic[i])
s = list(sorted(s))

dp = [0] * (n+1)
for i in range(0, n+1):
    a = 0
    max_a = -1
    for j in s:
        if i-j < 0:
            continue
        if i == j and dp[i-j] == 0:
            a = 1
        elif i - j > 0 and dp[i-j] > 0:
            a = dp[i-j] + 1
        if max_a < a:
            max_a = a
    dp[i] = max_a

def out(dp, dic, n, ans, ans_digit, lst):
    if len(ans) == ans_digit-1:
        for i in lst:
            if n == dic[i]:
                return ans + str(i)
    else:
        for i in lst:
            if n - dic[i] >= 0:
                if dp[n] -1 == dp[n-dic[i]]:
                    ans += str(i)
                    next_n = n - dic[i]
                    break
        return out(dp, dic, next_n, ans, ans_digit, lst)
    
print(out(dp, dic, n, '', dp[n], lst))