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 "climits"
#include "list"
#include "queue"
#include "stack"
#include "set"
#include "functional"
#include "algorithm"
#include "string"
#include "map"
#include "unordered_map"
#include "unordered_set"
#include "iomanip"
#include "cmath"
#include "random"
#include "bitset"
#include "cstdio"
#include "numeric"
#include "ctime"
#include "cassert"

using namespace std;

const long long int MOD = 1000000007;
//const int MOD = 998244353;

//long long int N, M, K, H, W, L, R;
long long int N, M, K, H, W, L, R;


int main() {
	ios::sync_with_stdio(false);
	cin.tie(0);

	cin >> N >> M;
	vector<int>v(10);
	vector<int>w({ 0,2,5,5,4,5,6,3,7,6 });
	for (int i = 0; i < M; i++) {
		cin >> K;
		v[K]++;
	}
	vector<string>dp(311);
	for (int i = 0; i <= 300; i++) {
		for (int j = 1; j <= 9; j++) {
			if (!v[j])continue;
			if (i&&dp[i].empty())continue;
			if (dp[i + w[j]].empty())dp[i + w[j]] = dp[i] + char('0' + j);
			else if (dp[i + w[j]].size() <= dp[i].size())dp[i + w[j]] = dp[i] + char('0' + j);
			else if (dp[i + w[j]].size() > dp[i].size() + 1)continue;
			dp[i + w[j]] = max(dp[i] + char('0' + j), dp[i + w[j]]);
		}
	}
	for (int i = 0; i <= 30; i++) {
//		cout << i << " " << dp[i] << endl;
	}
	while (N > 300) {
		int nx = 0;
		for (int i = 9; i >= 1; i--) {
			if (!v[i])continue;
			if (!nx)nx = i;
			if (w[nx] > w[i])nx = i;
		}
		N -= w[nx];
		cout << nx;
	}
//	cout << N << endl;
	cout << dp[N] << endl;
	return 0;
}