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>
#include <string>
#include <algorithm>
#include <cmath>
#include <cstdlib>
#include <bitset>
#include<vector>
#include<utility>
#include<fstream>
#include<queue>
#include <iomanip>
#include<numeric>
#include<set>
#include<map>
#include<functional>
using namespace std;
#define rep(i, k) for (i = 0; i < k; i++) 
typedef long long ll;
typedef pair<ll, ll> l_l;
int i, j;

int main() {
	ll a, b, k, n = 0, z = 0,x,y;
	ll p[1000] = {};
	cin >> x >> n;
	rep(i, n) {
		cin >> b;
		p[b]++;
	}

	for(i=1;i<101;i++) {
		if (p[i] == 1)continue;
		else {
			if (abs(x - i) < abs(x - z))z = i;
		}
	}
	
	

	cout << z;


	return 0;

}