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: Runtime Error)

#include<bits/stdc++.h>
#define rep(i, n) for (int i=0;i<(n);i++)
using namespace std;
typedef long long ll;

ll INF=10000005;


int main(void){
    int n, m;
    cin>>n>>m;
    vector<int> dp(n+1, -INF);
    vector<int> v(m);
    rep(i, m) cin>>v[i];
    vector<int> num={2, 5, 5, 4, 5, 6, 3, 7, 6};
    dp[0]=0;
    for(int i=1;i<=n;i++){
        rep(j, m){
            int number=num[v[j]-1];
            if(i-number<0) continue;
            dp[i]=max(dp[i-number]+1, dp[i]);
        }
    }
    vector<int> ans(dp[n]);
    sort(v.begin(), v.end(), greater<int>());
    int matchnum=n;
    for(int i=1;i<=dp[n];i++){//最上位から数えて何桁目かを示している
        rep(j, m){//どの数字を使うかをループしている
            //cout<<i<<j<<endl;
            if(matchnum-num[v[j]-1]<0) continue;
            if(dp[matchnum-num[v[j]-1]]==dp[n]-i){
                //cout<<i<<", "<<j<<endl;
                ans[i]=v[j];
                matchnum-=num[v[j]-1];
                break;
            }
        }
    }
    //rep(i, n) cout<<dp[i]<<endl;
    rep(i, dp[n]) cout<<ans[i+1];
    cout<<endl;


}