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 C++ (GCC 9.2.1) (judge verdict: Wrong Answer)

#include <iostream>

using namespace std;

bool CheckValue(int value, int p[], int n) {
	for (int i = 0; i < n; i++)
	{
		if (value == p[i]) return false;
	}
	return true;
}

int main()
{
	int x, n;
	int* p;
	cin >> x >> n;
	if (n == 0) {
		cout << x << endl;
		return 0;
	}

	p = new int[n];
	for (int i = 0; i < n; i++)
	{
		cin >> p[i];
	}

	int a = 1;
	int ans = 0;
	while (1) {
		if (CheckValue(x - a, p, n)) {
			ans = x - a;
			break;
		}
		if(CheckValue(x + a, p, n)){
			ans = x + a;
			break;
		}
		a++;
	}
	cout << ans << endl;

	delete[] p;
	return 0;
}