Problem:
Score : 300 points

Problem Statement

Given are an integer X and an integer sequence of length N: p_1, \ldots, p_N.

Among the integers not contained in the sequence p_1, \ldots, p_N (not necessarily positive), find the integer nearest to X, that is, find the integer whose absolute difference with X is the minimum. If there are multiple such integers, report the smallest such integer.

Constraints

1 \leq X \leq 100

0 \leq N \leq 100

1 \leq p_i \leq 100

p_1, \ldots, p_N are all distinct.

All values in input are integers.

Input

Input is given from Standard Input in the following format:

X N
p_1 ... p_N

Output

Print the answer.

Sample Input 1

6 5
4 7 10 6 5

Sample Output 1

8

Among the integers not contained in the sequence 4, 7, 10, 6, 5, the one nearest to 6 is 8.

Sample Input 2

10 5
4 7 10 6 5

Sample Output 2

9

Among the integers not contained in the sequence 4, 7, 10, 6, 5, the ones nearest to 10 are 9 and 11. We should print the smaller one, 9.

Sample Input 3

100 0

Sample Output 3

100

When N = 0, the second line in the input will be empty. Also, as seen here, X itself can be the answer.

Solution in Rust (1.42.0) (judge verdict: Accepted)

use std::io::stdin;

fn main() {
    let mut buf = String::new();
    std::io::stdin().read_line(&mut buf).unwrap();
    let l1 : Vec<i64> = buf.split_whitespace().filter_map(|x| x.parse().ok()).collect();
    let x = l1[0];
    let n = l1[1];

    buf.clear();
    stdin().read_line(&mut buf).unwrap();
    let l2 : Vec<i64>= buf.split_whitespace().filter_map(|x| x.parse().ok()).collect();
    let mut answer = -1;
    for p in 0 .. 102 {
        if l2.contains(&p) {
            continue;
        }

        if (p - x).abs() < (answer - x).abs() {
            answer = p;
        }
    }
    print!("{}",answer );
}