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 Ruby (2.3.3) (judge verdict: Wrong Answer)

def comp(a,b)
  a.each_with_index{|v,i|
    return 1 if v<b[i]
    return -1 if v>b[i]
  }
  0
end

n,m=gets.split.map(&:to_i)
a=gets.split.map(&:to_i)

Needed_match_num=[0,2,5,5,4,5,6,3,7,6]
digits={}
a.sort.reverse.each{|d|
  num=Needed_match_num[d]
  digits[num]||=d
}
a=digits.values
a.sort_by!{|d|Needed_match_num[d]}
dp=Array.new(n+9)
dp[n]=[0]*a.size
a.each_with_index{|d,i|
  nmn=Needed_match_num[d]
  n.downto(1){|j|
    if dp[j]
      temp=dp[j].dup
      temp[i]+=1
      if dp[j-nmn]
        if comp(dp[j-nmn],temp)==1
          dp[j-nmn]=temp
        end
      else
        dp[j-nmn]=temp      
      end
    end
  }
}

ans=[]

a.each_with_index{|d,i|
  ans+=[d]*dp[0][i]
}

puts ans.sort.reverse.join