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: Wrong Answer)

fun isNewBiggerThanOld(new: String, old: String) : Boolean {
    if (new.length != old.length) {
        return new.length > old.length
    }
    var i = 0
    while (i < new.length) {
        if (new[i] > old[i]) {
            return true
        } else if (new[i] < old[i]) {
            return false
        }
        i++
    }
    // Other
    return false
}

fun generateNext(str: String, number: Char) : String {
    val buffer = StringBuffer()
    var used = false
    var i = 0
    while (i < str.length) {
        val c = str[i]
        if (used) {
            buffer.append(str.substring(i))
            break
        }

        if (!used && number > c) {
            buffer.append(number)
            buffer.append(c)
            used = true
        } else {
            buffer.append(c)
        }
        i++
    }

    if (!used) {
        buffer.append(number)
    }

    return buffer.toString()
}
fun main(args : Array<String>) {
    val (N, M) = readLine()!!.split(" ").map { it.toInt() }
    val A = readLine()!!.split(" ").map { it.toCharArray()[0] }.sorted()
    val numToCost = listOf(-1, 2, 5, 5, 4, 5, 6, 3, 7, 6)
    val default = ""
    val dp = Array(N + 1, { default })

    (1..N).forEach { i ->
        var max = dp[i]
        A.forEach {
            val num = it
            val cost = numToCost[num - '0']
            if (i - cost >= 0) {
                if (dp[i-cost] == "") {
                    if (i - cost == 0) {
                        max = num.toString()
                    }
                } else {
                    val new = generateNext(dp[i-cost], num)
                    if (isNewBiggerThanOld(new, max)) {
                        max = new
                    }
                }
            }
        }
        dp[i] = max
    }
    println(dp[N])
}