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<stdio.h>
#include<stdlib.h>
#include<stdbool.h>
int cmp(const void *a,const void *b)
{
  return *(int*)a-*(int*)b;
} 
int main(){
  int x,n;
  scanf("%d%d",&x,&n);
  int i;
  int p[n];
  int ans1,ans2;
  for(i=0;i<n;i++){
  scanf("%d",&p[i]);
  }
  qsort(p,n,sizeof(int),cmp);
  ans1=x,ans2=x;
  
  for(i=0;i<n;i++){
    if(ans1==p[i]){
      ans1++;
    }
    if(ans2==p[i]){
      ans2--;
    }
  }
  bool b1=true,b2=true;
  for(i=0;i<n;i++){
    if(p[i]==ans1){
      b1=false;
    }
    if(p[i]==ans2){
      b2=false;
    }
  }
  int ans;
  if(abs(ans1-x)<abs(ans2-x)){
    if(b1==true){
    ans=ans1;
    }
    else{
      ans=ans2;
    }
  }
  else{
    if(b2==true){
    ans=ans2;
    }
    else{
      ans=ans1;
    }
  }
  
  printf("%d\n",ans);
  return 0;
}