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())
AList = list(map(int,input().split()))
AList.sort(reverse=True)
NList=[0,2,5,5,4,5,6,3,7,6]
CList=[]
minnum = (-1)*(10**10)
dp = [0]*(N+1)

for a in AList:
    u = NList[a]
    if (u in CList) == False:
        CList.append(u)

dp[0] = 0
for n in range(1,N+1):
    max1 = minnum
    for c in CList:
        if c <= n:
            if dp[n-c] == minnum:
                num = minnum
            else:
                num = dp[n-c]+1
            if max1 < num:
                max1 = num
    dp[n] = max1

keta = dp[N]
s = ''
nn = N
for n in range(keta):
    for a in AList:
        if dp[nn-NList[a]] == dp[nn]-1:
            s += str(a)
            nn -= NList[a]
            break
print(s)