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: Wrong Answer)

N,M=map(int,input().split())
A=list(map(int,input().split()))

T=[0,2,5,5,4,5,6,3,7,6]
B=[]
for i in A:
    B.append(T[i])
B=sorted(list(set(B)))

dp=[0 for i in range(N+1)]
dp2=['' for i in range(N+1)]
#for i in range(1,B[0]):
#    dp[i]=-1
#print(B)

for i in range(1,N+1):
    for j in B:
        if i-j>=0 and dp[i-j]!=-1:
            dp[i]=max(dp[i],dp[i-j]+1)
            #print(i,j,dp[i])
    if dp[i]==0:
        dp[i]=-1

c1,c2=N,N
U=[0 for i in range(8)]
while c1>0:
    c2-=1
    if dp[c2]+1==dp[c1]:
        U[c1-c2]+=1
        c1=c2
        
#print(U)
            
ans=""
if 9 in A:
    ans+='9'*U[6]
    U[6]=0
if 8 in A:
    ans+='8'*U[7]
if 7 in A:
    ans+='7'*U[3]
if 6 in A:
    ans+='6'*U[6]
if 5 in A:
    ans+='5'*U[5]
    U[5]=0
if 4 in A:
    ans+='4'*U[4]
if 3 in A:
    ans+='3'*U[5]
    U[5]=0
if 2 in A:
    ans+='2'*U[5]
if 1 in A:
    ans+='1'*U[2]

print(ans)