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)

fun main(args: Array<String>) {
    val (N, M) = listOfInt()
    val A = listOfInt().sortedDescending()
    val U = arrayListOf(0, 2, 5, 5, 4, 5, 6, 3, 7, 6)
    val V = A.map { U[it] }
    val S = Array<String?>(10001) { null }; S[0] = ""
    for (n in 1 .. N) {
        for (m in 0 until M) {
            val t = n - V[m]
            if (t >= 0 && S[t] != null) {
                if (S[n] == null) S[n] = ""
                if (S[n]!!.length <= S[t]!!.length) {
                    S[n] = S[t] + A[m]
                }
            }
        }
    }
    val ans = S[N]!!.split("").sortedDescending()
    println(ans.joinToString(""))
}
fun next() = readLine()!!
fun listOfString() = next().split(" ")
fun listOfInt() = listOfString().map(String::toInt)