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<bits/stdc++.h>
using namespace std;
#define int long long
#define rep(i,n) for(int i=0;i<(n);i++)
#define repr(i,n) for(int i=(n)-1;i>=0;i--)
#define repf(i,j,n) for(int i=(j);i<(n);i++)

const int maxn=1e4+20;
int dp[maxn];

void amax(int a,int b){if(a<b)a=b;}

signed main(){
int n,m;cin>>n>>m;
fill(dp,dp+maxn,-1);
dp[0]=0;

vector<int> digit={0,2,5,5,4,5,6,3,7,6};
rep(i,n){
repf(j,1,10){
if(dp[i]!=-1)amax(dp[i+digit[j]],dp[i]+1);
}
}
int num=dp[n];
int cnt=n;
rep(i,num){
repr(j,10){
if(cnt-digit[j]>=0&&dp[cnt]==dp[cnt-digit[j]]+1){
	cout<<j;cnt-=digit[j];break;
}
}
}
	
}