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>

int main()
{

    int x, n, a[100], i, w = 0, q = 0; //wは距離
    scanf("%d %d", &x, &n);

    w = x;

    if (n == 0)
    {
        printf("%d", x);
        return 0;
    }

    for (i = 0; i < n; i++)
    {
        scanf("%d", &a[i]);
    }

    int mode = 0;
    int j;

    for (j = x; j < 100; j++)
    {
        for (i = 0; i < n; i++)
        {
            if (j == a[i])
                mode = 1;
        }
        if (mode == 0)
            break;
        mode = 0;
    }

    int k;

    for (k = x; k > 0; k--)
    {
        for (i = 0; i < n; i++)
        {

            if (k == a[i])
            {
                mode = 1;
            }
        }
        if (mode == 0)
            break;
        mode = 0;
    }

    int y = 0, u = 0;
    y = j - x;
    u = x - k;

    if (w < y && w < u)
    {
        printf("%d", w);
    }

    else if (y < u)
    {
        printf("%d", j);

        return 0;
    }
    else
    {
        printf("%d", k);

        return 0;
    }

    printf("%d", w);

    return 0;
}