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 (2.4.0) (judge verdict: Wrong Answer)

from sys import stdout
printn = lambda x: stdout.write(str(x))
inn = lambda : int(input())
inl   = lambda: list(map(int, input().split()))
inm   = lambda:      map(int, input().split())
ins = lambda : input().strip()
DBG = True # and False
BIG = 999999999
R = 10**9 + 7

def ddprint(x):
  if DBG:
    print(x)

DEPMAX = 4

def foo(n,dep):
    if dep>DEPMAX or n<0:
        ret = "-1"
    elif n==0:
        ret = ""
    elif n%mn==0:
        ret = str(mni)*(n//mn)
    else:
        mxs = "-1"
        for x in a:
            v = foo(n-cs[x],dep+1)
            if v=="-1":
                continue
            vv = v+str(x)
            if int(vv)>int(mxs):
                mxs = vv
            vv = str(x)+v
            if int(vv)>int(mxs):
                mxs = vv
        ret = mxs
    #ddprint(f"foo n {n} k {k} ret {ret}")
    return ret

n,m = inm()
a = inl()
a.sort()
cs = [0,2,5,5,4,5,6,3,7,6]
mn = min([cs[x] for x in a])
for i in range(m-1,-1,-1):
    if cs[a[i]]==mn:
        mni = a[i]
        break
#k = (n+mn-1)//mn
#k = (n)//mn
#ddprint(f"mn {mn} mni {mni}")
#ddprint(a)
print(foo(n,0))