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;

#define ll long long
#define endl "\n"

int main ()
{
	
	ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    #define int ll
	
	int x, n;
	cin >> x >> n;

	bool taken[202];
	memset(taken, false, sizeof(taken));
	for (int i=1; i<=n; i++){
		int a;
		cin >> a;
		taken[a] = true;
	}
	
	for (int i=0; i<=100; i++){
		if (taken[x - i] == false){
			cout << x-i << endl;
			return 0;
		}
		if (taken[x+i] == false){
			cout << x+i << endl;
			return 0;
		}
	}

	return 0;
}