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 Java8 (OpenJDK 1.8.0) (judge verdict: Runtime Error)

import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.util.*;

public class Main {
    public static void main(String[] args) {
        Main main = new Main();
        main.solve();
    }
    public void solve() {
        Scanner scan = new Scanner(new BufferedReader(new InputStreamReader(System.in)));
        int N = scan.nextInt();
        int M = scan.nextInt();
        List<Integer> candidates = new ArrayList<>();
        for (int i = 0; i < M; i++) {
            candidates.add(scan.nextInt());
        }
        int[] match = {2,5,5,4,5,6,3,7,6};
        String[] dp = new String[10007];
        for (int i = 0; i < 10000; i++) {
            dp[i] = "-";
        }
        dp[0] = "";
        for (int i = 0; i <= N; i++) {
            if ("-".equals(dp[i])) {
                continue;
            }
            for (int a : candidates) {
                dp[i + match[a-1]] = max(dp[i + match[a-1]], dp[i] + a);
            }
        }
        System.out.println(dp[N]);
    }
    private String max(String a, String b) {
        if ("-".equals(a)) {
            a = b;
        }
        if (a.length() < b.length()) {
            return b;
        }
        if (a.length() > b.length()) {
            return a;
        }
        if (a.compareTo(b) < 0) {
            return b;
        }
        return a;
    }
}