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: Accepted)

import java.io.OutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.util.Arrays;
import java.util.Scanner;

/**
 * Built using CHelper plug-in
 * Actual solution is at the top
 *
 * @author HBonsai
 */
public class Main {
    public static void main(String[] args) {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        Scanner in = new Scanner(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        DMatchMatching solver = new DMatchMatching();
        solver.solve(1, in, out);
        out.close();
    }

    static class DMatchMatching {
        int[] cnt = new int[10];
        int[] memo = new int[10000 + 1];

        public void solve(int testNumber, Scanner in, PrintWriter out) {
            int n = Integer.parseInt(in.next());
            int M = Integer.parseInt(in.next());
            Arrays.fill(cnt, 1 << 29); // INF
            int[] use = new int[]{1 << 29, 2, 5, 5, 4, 5, 6, 3, 7, 6};
            while (in.hasNext()) {
                int x = Integer.parseInt(in.next());
                cnt[x] = use[x];
            }
            Arrays.fill(memo, -1);
            StringBuilder ans = new StringBuilder();
            while (n > 0) {
                for (int i = 9; i > 0; i--) {
                    if (dfs(n - cnt[i]) + 1 == dfs(n)) {
                        n -= cnt[i];
                        ans.append(i);
                        break;
                    }
                    if (i == 1) return;
                }
            }
            out.println(ans);
        }

        int dfs(int n) {
            if (n < 0) return -2;
            if (n == 0) return 0;
            if (memo[n] == -1) {
                for (int i = 1; i < 10; i++) {
                    memo[n] = Math.max(memo[n], dfs(n - cnt[i]) + 1);
                }
            }
            return memo[n];
        }

    }
}