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 Kotlin (1.0.0) (judge verdict: Accepted)

val ms = intArrayOf(2, 3, 4, 5, 6, 7, 8)
val num = intArrayOf(0,2,5,5,4,5,6,3,7,6)
val max_num = intArrayOf(0,0,0,0,0,0,0,0,0,0)

fun main(args: Array<String>) {
    val (n, m) = readLine()!!.split(" ").map(String::toInt)
    val a = readLine()!!.split(" ").map(String::toInt)
    for(i in 0 until m){
        max_num[num[a[i]]] = Math.max(max_num[num[a[i]]], a[i])
    } 
    val dp = Array<Int>(n+1, {-100000000})
    for(i in 0 until m){
        if(num[a[i]] > n) continue
        dp[num[a[i]]] = Math.max(dp[num[a[i]]], 1)
    }
    dp[0] = 0
    for(i in 2..n){
        for(j in 2..9){
            if(max_num[j] == 0) continue
            if(i-j >=0) dp[i] = Math.max(dp[i], dp[i-j]+1) 
        }
    }
    var cur = n
    while(cur > 0){
        var mx = -1
        var mm = 0
        for(i in 2..9){
            if(max_num[i] == 0) continue
            if(cur-i >= 0){
                if(mx < max_num[i] && dp[cur]==dp[cur-i]+1){
                    mx = max_num[i]
                    mm = i
                }
            }
        }
        print(mx)
        cur -= mm
    }
    println()
}