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)

N, M = map(int, input().split())
A = list(map(int, input().split()))
honsuu = [0,2,5,5,4,5,6,3,7,6]
aval = []
for a in A:
  aval += [honsuu[a]]
aval.sort()
 
dp = [0]+ [-float("INF")]*N 

for i in range(1,N+1):
  for b in aval:
    if i < b:
      continue
    elif dp[i-b] >= 0:
      dp[i] = dp[i-b] + 1
      break

A.sort(reverse=True)
ans = []
for i in range(dp[N],1,-1):
  for a in A:
    if N - honsuu[a] < 0:continue
    if dp[N - honsuu[a]] == dp[N] - 1:
      N -= honsuu[a]
      ans += [a]
      break
      
final = 0
for i in range(10):
  if i in A and honsuu[i] == N:
    final = i
ans += [final]
print(''.join(map(str, ans)))