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;
use std::io::{stdout, Write};
use std::cmp;

fn main() {
    let mut X = String::new();
    let mut P = String::new();
    io::stdin().read_line(&mut X);
    io::stdin().read_line(&mut P);
    let mut vec :Vec<&str> = X.trim().split_whitespace().collect();
    let mut x :usize = vec[0].parse().unwrap();
    let mut n :usize = vec[1].parse().unwrap();
    let mut vecP :Vec<usize> = P.trim().split_whitespace().map(|e| e.parse::<usize>().unwrap()).collect();
    let mut x1 :usize = x;
    let mut x2 :usize = x;
    loop{
        if x1 == 0{
            println!("{}",x1);
            return()
        }else if !vecP.contains(&x1){
            println!("{}",x1);
            return()
        }else if !vecP.contains(&x2){
            println!("{}",x2);
            return()
        }
        x1 -=1;
        x2 +=1;
    }
}