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 <iostream>
#include <algorithm>
using namespace std;
typedef long long ll;
int main(){
  ll x,n,ans=0,t=0,r=0;cin>>x>>n;
  ll a[n];
  for(int i=0;i<n;i++){
    cin>>a[i];
  }
  sort(a,a+n);
  for(int i=0;i<=100;i++){
    for(int j=0;j<n;j++){
      if(a[j]!=x+i){t++;}
      if(a[j]!=x-i){r++;}
    }
      if(r==n){ans=x-i;break;}
      if(t==n){ans=x+i;break;}
    t=0;r=0;
  }
  if(n==0){ans=x;}
  cout << ans<<endl;
}