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"

int main(void)
{
  int X,N;
  int i,n=0,ans;
  unsigned int p[100];
  unsigned int check[100] = {0};
  
  //input
  scanf("%d %d",&X,&N);
  for(i=0;i<N;i++)
  {
  	scanf("%d",&p[i]);
    check[p[i]] = p[i];
  }
  //check
	while(1)
    {
    	if(N==0)
        {
          ans=X;
          break;
    	}else if(check[X-n]==0){
          ans =X-n;
        	break;
        }else if(check[X+n]==0){
          ans =X+n;
          break;
        }
      n++;
    }
  //output
  printf("%d",ans);

  
  return 0;
}