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)

import collections
from time import sleep
def main():
	match = {1:2, 2:5, 3:5, 4:4, 5:5, 6:6, 7:3, 8:7, 9:6}
	count = collections.defaultdict(int)
	n, m = map(int, input().split())
	ms = list(map(int, input().split()))
	ms.sort()
	ms.reverse()
	use_match = []
	for i in range(m):
		if count[match[ms[i]]] == 0:
			use_match.append([match[ms[i]], ms[i]])
		count[match[ms[i]]] += 1
	sorted(use_match, key = lambda x: x[0])
	dp = [-1]*(n+1)
	dp[0] = 0
	for i in range(n+1):
		maximum = -1
		for k in use_match:
			if i - k[0] >= 0:
				current = dp[i-k[0]] + 1
				if maximum < current:
					maximum = current
		if maximum != -1:
			dp[i] = maximum
	num = n
	ans = ""
	while num > 0:
		for k in use_match:
			if dp[num] - dp[num - k[0]] == 1:
				ans += str(k[1])
				num -= k[0]
				break
	print(ans)


if __name__ == '__main__':
	main()