Buggy python submission (verdict: Runtime Error):
N,M=map(int,input().split())
A=list(map(int,input().split()))
M=[0,2,5,5,4,5,6,3,7,6]

#まず最高何桁の数にできるか考えよう.

USE=[M[a] for a in A]
USE=sorted(set(USE))

ANSLIST=[0]
def dfs(i,NOW):
    if ANSLIST[0]!=0:
        return
    ANS=0
    if NOW==N:
        L=sorted(list(i),reverse=True)
        #print(L)
        
        ANSLIST[0]=int(("".join(L)))
        return

    elif NOW>N:
        return 
    else:
        for a in A:
            dfs(i+str(a),NOW+M[a])


A.sort(reverse=True)
A.sort(key=lambda x:M[x])
dfs("",0)

x=ANSLIST[0]
stx=str(x)
from collections import Counter
counter=Counter(stx)

i=1
j=1
for ij in range(2,19):
    for i in range(1,ij):
        j=ij-i
        for k in range(1,10):
            for l in range(1,10):
                if i in A and j in A and k in A and l in A and counter[i]>0 and counter[j]>0:
                    x=min(counter[i],counter[j])
                    counter[i]-=x
                    counter[j]-=x
                    counter[k]+=x
                    counter[l]+=x

ANS=""
for i in range(9,-1,-1):
    ANS+=str(i)*counter[str(i)]

print(ANS)



Fixed submission:
import sys
sys.setrecursionlimit(10**9)

N,M=map(int,input().split())
A=list(map(int,input().split()))
M=[0,2,5,5,4,5,6,3,7,6]

#まず最高何桁の数にできるか考えよう.

SET_A=set(A)

ANSLIST=[0]
def dfs(i,NOW):
    if ANSLIST[0]!=0:
        return
    ANS=0
    if NOW==N:
        L=sorted(list(i),reverse=True)
        #print(L)
        
        ANSLIST[0]=int(("".join(L)))
        return

    elif NOW>N:
        return 
    else:
        for a in A:
            dfs(i+str(a),NOW+M[a])


A.sort(reverse=True)
A.sort(key=lambda x:M[x])
dfs("",0)

x=ANSLIST[0]
stx=str(x)
from collections import Counter
counter=Counter(stx)


import itertools
for i,j,k in list(itertools.combinations(range(1,10),3)):
    for l,m,n in list(itertools.combinations(range(1,10),3)):
        if i in SET_A and j in SET_A and k in SET_A and l in SET_A and m in SET_A and n in SET_A and M[i]+M[j]+M[k]==M[l]+M[m]+M[n] and \
           counter[str(i)]>0 and counter[str(j)]>0 and counter[str(k)]>0 and (n>k or (n==k and m>j) or (n==k and m==j and l>i)):
                    x=min(counter[str(i)],counter[str(j)],counter[str(k)])
                    counter[str(i)]-=x
                    counter[str(j)]-=x
                    counter[str(k)]-=x
                    counter[str(l)]+=x
                    counter[str(m)]+=x
                    counter[str(n)]+=x

for i,j in list(itertools.combinations(range(1,10),2)):
    for l,m in list(itertools.combinations(range(1,10),2)):
        if i in SET_A and j in SET_A and l in SET_A and m in SET_A and M[i]+M[j]==M[l]+M[m] and \
           counter[str(i)]>0 and counter[str(j)]>0 and (m>j or (m==j and l>i)):
                    x=min(counter[str(i)],counter[str(j)])
                    counter[str(i)]-=x
                    counter[str(j)]-=x

                    counter[str(l)]+=x
                    counter[str(m)]+=x

for i in range(1,10):
    for l in range(1,10):
        if i in SET_A and l in SET_A and l>i and M[i]==M[l] and counter[str(i)]>0:
            counter[str(l)]+=counter[str(i)]
            counter[str(i)]=0



ANS=""
for i in range(9,-1,-1):
    ANS+=str(i)*counter[str(i)]

print(ANS)

Buggy python submission (verdict: Runtime Error):
import sys

N,M=map(int,input().split())
A=list(map(int,input().split()))
M=[0,2,5,5,4,5,6,3,7,6]

def match(i):
    ANS=0
    for s in str(i):
        ANS+=M[int(s)]

    return ANS
        

def dfs(i,NOW):
    if NOW==N:
        L=sorted(list(i),reverse=True)
        
        print("".join(L))
        sys.exit()
    elif NOW>N:
        return
    else:
        for a in A:
            dfs(i+str(a),NOW+M[a])


A.sort(reverse=True)
#print(A)
A.sort(key=lambda x:M[x])
#print(A)

dfs("",0)

Fixed submission:
import sys
sys.setrecursionlimit(10**9)

N,M=map(int,input().split())
A=list(map(int,input().split()))
M=[0,2,5,5,4,5,6,3,7,6]

#まず最高何桁の数にできるか考えよう.

SET_A=set(A)

ANSLIST=[0]
def dfs(i,NOW):
    if ANSLIST[0]!=0:
        return
    ANS=0
    if NOW==N:
        L=sorted(list(i),reverse=True)
        #print(L)
        
        ANSLIST[0]=int(("".join(L)))
        return

    elif NOW>N:
        return 
    else:
        for a in A:
            dfs(i+str(a),NOW+M[a])


A.sort(reverse=True)
A.sort(key=lambda x:M[x])
dfs("",0)

x=ANSLIST[0]
stx=str(x)
from collections import Counter
counter=Counter(stx)


import itertools
for i,j,k in list(itertools.combinations(range(1,10),3)):
    for l,m,n in list(itertools.combinations(range(1,10),3)):
        if i in SET_A and j in SET_A and k in SET_A and l in SET_A and m in SET_A and n in SET_A and M[i]+M[j]+M[k]==M[l]+M[m]+M[n] and \
           counter[str(i)]>0 and counter[str(j)]>0 and counter[str(k)]>0 and (n>k or (n==k and m>j) or (n==k and m==j and l>i)):
                    x=min(counter[str(i)],counter[str(j)],counter[str(k)])
                    counter[str(i)]-=x
                    counter[str(j)]-=x
                    counter[str(k)]-=x
                    counter[str(l)]+=x
                    counter[str(m)]+=x
                    counter[str(n)]+=x

for i,j in list(itertools.combinations(range(1,10),2)):
    for l,m in list(itertools.combinations(range(1,10),2)):
        if i in SET_A and j in SET_A and l in SET_A and m in SET_A and M[i]+M[j]==M[l]+M[m] and \
           counter[str(i)]>0 and counter[str(j)]>0 and (m>j or (m==j and l>i)):
                    x=min(counter[str(i)],counter[str(j)])
                    counter[str(i)]-=x
                    counter[str(j)]-=x

                    counter[str(l)]+=x
                    counter[str(m)]+=x

for i in range(1,10):
    for l in range(1,10):
        if i in SET_A and l in SET_A and l>i and M[i]==M[l] and counter[str(i)]>0:
            counter[str(l)]+=counter[str(i)]
            counter[str(i)]=0



ANS=""
for i in range(9,-1,-1):
    ANS+=str(i)*counter[str(i)]

print(ANS)