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: Accepted)

#include <bits/stdc++.h>
using namespace std;

int main()
{
	int X, N;
	int p[100];
	int flag = 0;
	int min = 100;
	int n_closest = 100;

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

	for (int n = 200; n >= 0; n--) {
		for (int i = 0; i < N; i++) {
			if (n == p[i])
				flag = 1;
		}
		if (flag == 0) {
			if (min >= abs(X - n)) {
				min = abs(X - n);
				n_closest = n;
			}
		}
		flag = 0;
	}

	cout << n_closest << endl;

	return 0;
}