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 C++14 (GCC 5.4.1) (judge verdict: Wrong Answer)

#include <iostream>
#include <algorithm>
#include <cmath>
#include <vector>
#include <queue>
#define rep(i,n) for(int i=0;i<n;i++)
#define ll long long int
#define MAX 1000000007
using namespace std;

int main(void){
	int n,m;
	cin>>n>>m;
	int num[9]={2,5,5,4,5,6,3,7,6}, dp[n+1],a[m];
	rep(i,m)cin>>a[i];
	sort(a,a+m);

	rep(i,n+1)dp[i]=-1000000;
	dp[0]=0;
	rep(i,m){
		rep(j,n-1){
			if(dp[j]>=0 && j+num[a[i]-1]<=n && dp[j+num[a[i]-1]]<dp[j]+1)dp[j+num[a[i]-1]]=dp[j]+1;
		}
	}


	rep(i,m){
		while(dp[n-num[a[m-1-i]-1]]+1 == dp[n]){
			cout<<a[m-1-i];
			n-=num[a[m-1-i]-1];
		}
	}
	
	cout<<endl;
	return 0;
}