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<bits/stdc++.h>

using namespace std;

typedef long long int lli;
typedef vector<int> vi;
typedef pair<int, int> pi;
typedef vector<pair<int, int>> vii;

#define F first
#define S second
#define PB push_back
#define MP make_pair
#define REP(i,a,b) for(int i=a;i<b;i++)

#define FASTIO ios_base::sync_with_stdio(false);cin.tie(NULL);cout.tie(NULL);

int main() {
	#ifndef ONLINE_JUDGE
	freopen("input.txt","r",stdin);
	freopen("output.txt","w",stdout);
	#endif
	
	FASTIO

	int T=1;
//	cin >> T;

	while(T--) {
		int x,n,input;
		cin >> x >> n;

		int dat[102]={};

		REP(i,0,n) {
			cin >> input;
			dat[input]++;
		}

		REP(i,1,min(x+1,101-x)) {
			if(dat[x-i]==0) {
				x-=i;
				break;
			}
			if(dat[x+i]==0) {
				x+=i;
				break;
			}
		}

		cout << x;
	}

	return 0;
}