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 PyPy3 (7.3.0) (judge verdict: Accepted)

import sys
input = sys.stdin.buffer.readline

N, M = map(int, input().split())
A = list(map(int, input().split()))
Need = [-1, 2, 5, 5, 4, 5, 6, 3, 7, 6]
Usable = {}
for a in A:
    if Need[a] in Usable:
        for key, value in Usable.items():
            if Need[a] == key and a > value:
                Usable[key] = a
    else:
        Usable[Need[a]] = a
Num = [-1] * (N + 1)
Num[0] = 0
for i in range(1, N+1):
    for u, v in Usable.items():
        if i < u:
            continue
        if Num[i - u] >= 0:
            if Num[i - u] == 0:
                Num[i] = max(v, Num[i])
            elif Num[i] < Num[i - u] * 10 + v:
                Num[i] = Num[i - u] * 10 + v

print(Num[N])