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

int main() {
    int x, n;
    int p[100];
    int i, j;
    int ans, mans, flag;
    scanf("%d %d", &x, &n);
    for (i=0;i<n;i++) scanf("%d", &p[i]);
    ans=1000;
    mans=1000;
    if (n==0) {
        printf("%d\n", x);
        return 0;
    }
    for (j=x;j<102;j++) {
        flag=1;
        for (i=0;i<n;i++) {
            if(p[i]==j) flag=0;
        }
        if (flag) {
            ans=j;
            break;
        }
    }
    for (j=x;j>-101;j--) {
        flag=1;
        for (i=0;i<n;i++) {
            if(p[i]==j) flag=0;
        }
        if (flag) {
            mans=j;
            break;
        }
    }
    if (abs(x-ans)>abs(x-mans)) {
        printf("%d\n", mans);
    } else if (abs(x-ans)==abs(x-mans)) {
        printf("%d\n", mans);
    } else {
        printf("%d\n", ans);
    }
    return 0;
}