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)

n,m = gets.split.map(&:to_i)
num = gets.split.map(&:to_i)
dp = Array.new(n+1,0)
st = [0,2,5,5,4,5,6,3,7,6]
num.sort!
stick = []
m.times {|i| stick.push(st[num[i]])}
for i in 2..n
  inst = 0
  for j in 0..m-1
    if stick[j] <= i && inst < dp[i-stick[j]]+1
      inst = dp[i-stick[j]]+1
    end
  end
  dp[i] = inst
end
ans = []
count = 1
for i in 1..dp[-1]-1
  for j in 1..m
    if count+stick[-j] <= n && dp[-count] == dp[-count-stick[-j]]+1
      count += stick[-j]
      ans.push(num[-j])
      break
    end
  end
end
for i in 1..m
  if count+stick[-i] == n+1
    ans.push(num[-i])
  end
end
puts ans.join