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 proconio::{fastout, input};

#[fastout]
fn main() {
    input! {
        x: i64,
        n: usize,
        p_vec: [usize; n],
    }

    let mut d: [i64; 102] = [-1; 102];
    p_vec.iter().for_each(|p| {
        d[*p] = 1;
    });
    let mut ans: (i64, i64) = (9999999, -1);
    (0..=101).for_each(|i| {
        if d[i] != 1 {
            let dif = (x - i as i64).abs();
            ans = if ans.0 > dif {
                (dif, i as i64)
            } else if ans.0 == dif && ans.1 > i as i64 {
                (dif, i as i64)
            } else {
                ans
            };
        }
    });
    println!("{}", ans.1)
}