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>
int main(void){
    // Your code here!
    
    int entry_point,entry_num;
    int entry[100]={0};
    int i,flg;
    int abs_num=0,answer;
    
    //入力
    scanf("%d",&entry_point); //整数X
    scanf("%d",&entry_num); //入力個数
    
    for(i=0; i<entry_num; i++){
        scanf("%d",&entry[i]);
    }
    

    while(1){
        flg=0;
        answer = entry_point - abs_num;
        for(i=0; i<entry_num; i++){
            if(answer == entry[i]){
                flg = 1;
                break;
            }
        }
        if(flg == 0){
            //発見
            break;
        }
        flg=0;
        answer = entry_point + abs_num;
        for(i=0; i<entry_num; i++){
            if(answer == entry[i]){
                flg = 1;
                break;
            }
        }
        if(flg == 0){
            //発見
            break;
        }
        abs_num++;
    }
        
        
    printf("%d\n",answer);
    
}