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)

use std::io::Read;

fn main() {
    const ms: [i32; 10] = [0, 2, 5, 5, 4, 5, 6, 3, 7, 6];
    
    let mut buf = String::new();
    std::io::stdin().read_to_string(&mut buf).unwrap();
    
    let mut iter = buf.split_whitespace();
    
    let mut n: i32 = iter.next().unwrap().parse().unwrap();
    iter.next();
    
    let mut ns: Vec<usize> = iter.map(|n| n.parse::<usize>().unwrap()).collect();
    ns.sort_by(|&a, &b| {
        let am = ms[a] as usize;
        let bm = ms[b] as usize;
        if am != bm {
            am.cmp(&bm)
        } else {
            b.cmp(&a)
        }
    });
    println!("{:?}", ns);
    
    let mut rs: Vec<usize> = Vec::new();
    calc(n, &ns, &ms, &mut rs);
    
    rs.sort_by(|a, b| b.cmp(&a));
    for i in rs {
        print!("{}", i);
    }
    println!("");
}

fn calc(n: i32, ns: &[usize], ms: &[i32], rs: &mut Vec<usize>) -> i32 {
    if n > 0 {
        for &i in ns {
            if calc(n - ms[i], ns, ms, rs) == 0 {
                rs.push(i);
                return 0;
            };
        }
    }
    n
}