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 <stdio.h>
#include <stdlib.h>

int main(void){
    
    int x,n;
    scanf("%d %d",&x,&n);
    
    int p[101]={0};
    
    for(int i=1;i<=n;i++){
    scanf("%d",&p[i]);
    }
    int tmp;
    
    for (int i=1; i<=n; ++i) {
        for (int j=i+1; j<=n; ++j) {
              if (p[i] > p[j]) {
               tmp =  p[i];
              p[i] = p[j];
              p[j] = tmp;
             }
        }
    }
    
    for (int i=1; i<=n; i++) {
        if(x<p[i]){
        printf("%d",x);
        return 0;
        }
        
        if(x==p[i]){
            for(int j=1;j<i;j++){
             if(p[i-j]!=x-j){
                printf("%d",x-j);
                return 0;
             }   
             if(p[i+j]!=x+j){
                printf("%d",x+j);
                return 0;
             }     
            }
                printf("%d",x-i);
                return 0;
        }
    }
    
    printf("%d",x);
    return 0;
}