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: Wrong Answer)

import java.util.*;

public class Main {

	public static void main(String[] args) {
		// TODO Auto-generated method stub

		Scanner sc = new Scanner(System.in);
		int N = sc.nextInt();
		int M = sc.nextInt();
		ArrayList<Integer> list=new ArrayList<>();
		int[] set={0,2,5,5,4,5,6,3,7,6};
		
		int[] a=new int[M];
		
		String[] help=new String[N+5];
		
		help[0]="";
		
		for(int i = 0; i<M; i++){
		
			a[i]= sc.nextInt();
		
		}
		
		for(int i = 0; i<=N; i++){
		
			for(int j = 0; j<M; j++){
			
				if(i>=set[a[j]] && help[i-set[a[j]]]!=null){
				
					if(check(help[i-set[a[j]]]+a[j],help[i])){
					
						help[i]=help[i-set[a[j]]]+a[j];
					}
					
				}
				
			}
			
		}
		
		System.out.println(help[N]);
		
	}



	static boolean check(String A,String B){
		if(B==null || A.length()>B.length()){
			return true;
		}
		if(A.length()<B.length()){
			return false;
		}
		return A.length() - B.length()>0;
	}
}