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: Accepted)

#include "bits/stdc++.h"
#define _overload3(_1,_2,_3,name,...) name
#define _rep(i,n) repi(i,0,n)
#define repi(i,a,b) for(int i=int(a),i##_len=(b);i<i##_len;++i)
#define BUGAVOID(x) x
#define rep(...) BUGAVOID(_overload3(__VA_ARGS__,repi,_rep,_rep)(__VA_ARGS__))
#define sz(c) (int)(c.size())
#define all(c) c.begin(),c.end()
#define mp make_pair
#define write(x) cout<<(x)<<"\n"
using namespace std; typedef long long ll;
typedef vector<int> vi; typedef vector<ll> vll; template<class T, class U>using vp = vector<pair<T, U>>;
template<class T>using vv = vector<vector<T>>; template<class T, class U>using vvp = vv<pair<T, U>>;
template<class T>vv<T> vvec(size_t n, size_t m, T v) { return vv<T>(n, vector<T>(m, v)); }
template<class T>bool chmax(T& a, const T& b) { return a < b ? a = b, 1 : 0; }
template<class T>bool chmin(T& a, const T& b) { return b < a ? a = b, 1 : 0; }
constexpr int INF = 1 << 28, MAX = 1e5 + 5, MOD = 1e9 + 7;
constexpr ll LINF = 1ll << 60; constexpr double EPS = 1e-6;
constexpr int dy[4] = { 0,1,0,-1 }, dx[4] = { 1,0,-1,0 };
struct aaa { aaa() { cin.tie(0); ios::sync_with_stdio(0); }; }aaaa;

// 1 2 3 4 5 6 7 8 9
// 2 5 5 4 5 6 3 7 6
const int require[] = { 0, 2, 5, 5, 4, 5, 6, 3, 7, 6 };

int N, M;
vi A;
vi dp;

int main() {
    cin >> N >> M;
    A.resize(M);
    rep(i, M) cin >> A[i];
    sort(all(A));
    reverse(all(A));

    dp.resize(N + 1, -INF);
    dp[0] = 0;
    rep(i, 1, N + 1) {
        rep(j, M) {
            if (i - require[A[j]] >= 0) {
                chmax(dp[i], dp[i - require[A[j]]] + 1);
            }
        }
    }

    int Nrest = N;
    rep(i, dp[N]) {
        rep(j, M) {
            if (Nrest >= require[A[j]] && dp[Nrest - require[A[j]]] == dp[Nrest] - 1) {
                cout << A[j];
                Nrest -= require[A[j]];
                break;
            }
        }
    }
    puts("");
}