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<string.h>
#include<math.h>

#define NIL -1
#define zizyou(a,b) pow(((a)-(b)),2.0)

int main()
{
    int target, length;
    int ini_array[100];
    int answer_num = 0;
    int answer_abs = 20000;
    int answer_array[101];

    scanf("%d %d", &target, &length);

    for (int i = 0; i<=101; i++)
    {
        answer_array[i] = i;
    }

    for (int i = 0; i<length; i++)
    {
        scanf("%d", &ini_array[i]);
        answer_array[ini_array[i]] = NIL;
    }

    for (int i = 0; i<=101; i++)
    {
        if (answer_array[i] == NIL)
        {
            continue;
        }

        if (zizyou(target, answer_array[i]) < answer_abs)
        {
            answer_abs = zizyou(target, answer_array[i]);
            answer_num = answer_array[i];
        }
    }

    printf("%d", answer_num);


    return 0;
}