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++ (Clang 10.0.0) (judge verdict: Wrong Answer)

#include <algorithm>
#include <bitset>
#include <complex>
#include <deque>
#include <exception>
#include <fstream>
#include <functional>
#include <iomanip>
#include <ios>
#include <iosfwd>
#include <iostream>
#include <istream>
#include <iterator>
#include <limits>
#include <list>
#include <locale>
#include <map>
#include <memory>
#include <new>
#include <numeric>
#include <ostream>
#include <queue>
#include <set>
#include <sstream>
#include <stack>
#include <stdexcept>
#include <streambuf>
#include <string>
#include <typeinfo>
#include <utility>
#include <valarray>
#include <vector>

using namespace std;
#define int long long
#define ld long double
#define all(x) x.begin(),x.end()
#define max3(a,b,c) max(a,max(b,c))
#define min3(a,b,c) min(a,min(b,c))
#define vi vector<int>
#define vstr vector<string>
#define vbool vector<bool>
#define vvi vector<vector<int> >
#define mii map<int,int>
#define pb push_back
#define pii pair<int,int>
#define vpair vector<pii > 
#define mkp make_pair
#define scan(a,n) for(int i =0 ; i<n ; i++) cin>>a[i]
#define print(a,n) for(int i = 0 ; i < n ; i++) {cout<<a[i]<<' ';}cout<<'\n'
#define mem(a,v) memset(a,v,sizeof(a))
#define loop(i,a,b) for (int i = a; i < b; i++)
#define loope(i,a,b) for (int i = a; i <= b; i++)
#define FastIO ios_base::sync_with_stdio(false);cin.tie(NULL);cout.tie(NULL)
#define PRECISION std::cout.unsetf ( std::ios::fixed );std::cout.precision(9)
#define PI 3.14159265
#define S second
#define F first
#define CHECK cout<<"CHEDEDWB"<<endl
int mod = 1e9+7;
int inf = 1e18;
int m_inf = INT_MIN;

void solve()
{
	int x,n;
	cin>>x>>n;
	if(n==0)
		cout<<x<<endl;
	else
	{
		int p=0,q=0;
		vector<bool> ans(101,false);
		vi arr(n);
		loop(i,0,n)
		{
			cin>>arr[i];
			ans[arr[i]] = true;
		}
		sort(all(arr));
		loop(i,x,101)
		{
			if(ans[i]==false)
				{
					p = i;
					break;
				}
		}
		for(int i = x;i>0;i--)
		{
			if(ans[i]==false)
				{
					q = i;
					break;
				}
		}
		if(abs(x-p)<abs(x-q))
			cout<<p<<endl;
		else
			cout<<q<<endl;
	}
}

int32_t main()
{
	FastIO; PRECISION;
	int t = 1;
	//cin>>t;
	while(t--)
		solve();
	return 0;
}