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>
#define ll long long int
#define loop(i,a,b) for(i=a;i<b;i++)
#define INF 10000000000
#define pb push_back
#define lim 100001

using namespace std;
int main()
{ll x,n,i,j,ans=0,diff=INF;
	
	cin>>x>>n;
ll a[n];
	loop(i,0,n)
	cin>>a[i];

	
    
	loop(i,0,102){
		loop(j,0,n)
		if(a[j]==i)
			break;
		if(j==n && diff>abs(x-i))
		{
			ans=i; diff=abs(x-i);
		}}

		cout<<ans<<endl;
return 0;
	}