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 Go (1.14.1) (judge verdict: Wrong Answer)

package main

import "fmt"

func checkContain(a int, arr [100]int) bool {
	for i := 0; i < 100; i++ {
		if arr[i] == a {
			return true
		}
	}
	return false
}

func main() {
	var x, n int
	var arr [100]int
	fmt.Scanf("%d %d \n", &x, &n)
	for i := 0; i < n; i++ {
		fmt.Scanf("%d", &arr[i])
	}
	if n == 0 {
		fmt.Println(x)
	} else {
		var count = 0
		for true {
			if !checkContain(x-count, arr) {
				fmt.Println(x - count)
				break
			}
			if !checkContain(x+count, arr) {
				fmt.Println(x + count)
				break
			}
			count++
		}
	}
}