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 Rust (1.15.1) (judge verdict: Wrong Answer)

macro_rules! input {
    (source = $s:expr, $($r:tt)*) => {
        let mut iter = $s.split_whitespace();
        input_inner!{iter, $($r)*}
    };
    ($($r:tt)*) => {
        let s = {
            use std::io::Read;
            let mut s = String::new();
            std::io::stdin().read_to_string(&mut s).unwrap();
            s
        };
        let mut iter = s.split_whitespace();
        input_inner!{iter, $($r)*}
    };
}

macro_rules! input_inner {
    ($iter:expr) => {};
    ($iter:expr, ) => {};

    ($iter:expr, $var:ident : $t:tt $($r:tt)*) => {
        let $var = read_value!($iter, $t);
        input_inner!{$iter $($r)*}
    };
}

macro_rules! read_value {
    ($iter:expr, ( $($t:tt),* )) => {
        ( $(read_value!($iter, $t)),* )
    };

    ($iter:expr, [ $t:tt ; $len:expr ]) => {
        (0..$len).map(|_| read_value!($iter, $t)).collect::<Vec<_>>()
    };

    ($iter:expr, chars) => {
        read_value!($iter, String).chars().collect::<Vec<char>>()
    };

    ($iter:expr, usize1) => {
        read_value!($iter, usize) - 1
    };

    ($iter:expr, $t:ty) => {
        $iter.next().unwrap().parse::<$t>().expect("Parse error")
    };
}

fn main() {
    input!{
        n: usize,
        m: usize,
        am: [usize; m]
    }
    println!("{}", solve(n,m,am));
}

use std::collections::VecDeque;
fn solve(n: usize, _m: usize, am: Vec<usize>) -> String {
    let match_nums = vec![0,2,5,5,4,5,6,3,7,6];
    let match_seq = vec![1,7,4,5,3,2,9,6,8];
    let sorted_am: Vec<usize> = match_seq.into_iter().filter(|x| am.contains(x)).collect();
    let mut breadth: VecDeque<(String, usize)> = VecDeque::new();
    for &a in &sorted_am {
        let num = match_nums[a];
        if num > n {
            break;
        }
        if num == n {
            return a.to_string();
        }
        breadth.push_back((a.to_string(), n - num));
    }
    let mut answer = String::new();
    'outer: while let Some((x, nx)) = breadth.pop_front() {
        if nx == 0 {
            answer = x;
            break;
        }
        for &a in sorted_am.iter().rev() {
            let num = match_nums[a];
            if num > nx {
                continue;
            }
            breadth.push_front((format!("{}{}", x, a), nx - num));
        }
    }
    let mut answer:Vec<_> = answer.chars().collect();
    answer.sort();
    answer.reverse();
    answer.into_iter().collect::<String>()
}

#[test]
fn solve_test() {
    assert_eq!(solve(20,4,vec![3,7,8,4]), "777773");
    assert_eq!(solve(101,9,vec![9,8,7,6,5,4,3,2,1]), "71111111111111111111111111111111111111111111111111");
    assert_eq!(solve(15,3,vec![5,4,6]), "654");
}