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>
using namespace std;
 
int main(){
  
  int X,N;
  
  int P[110];
  
  cin>>X>>N;
  
  if(N == 0){
    cout<<X;
    return 0;
  
  
  }
  
  for(int i = 0;i < N;i++){
    cin>>P[i];
  
  }
  
  int res = 200;
  
  int T = 0;
  int Tn = 0;
  
  int T2 = 0;
  int T2n = 0;
  
  
  for(int i = 101;i >= 1;i--){
    
    bool aru = false;
    for(int j = 0;j < N;j++){
      if(i == P[j])aru = true;
    
    }
    
    if(aru){
    
    }else{
      int tmp = abs(X-i);
      if(min(tmp,res) == tmp){
        res = tmp;
        Tn = res;
        T = i;
      
      }
    
    }
    
    }
  
  res = 200;
  
    for(int i = -101;i <= -1;i++){
      int tmp = abs(X-i);
      if(min(tmp,res) == tmp){
        res = tmp;
        T2n = res;
        T2 = i;
    }
      
    }
      
      if(Tn > T2n){
        cout<<T2;
      }else{
        cout<<T;
      
      }
  
  
  return 0;
}