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){
    int a,b,c,i,min=1000,num;
    int flg[102];
    scanf("%d%d",&a,&b);
    for(i=0;i<=101;i++) flg[i]=0;
    for(i=0;i<b;i++){
        scanf("%d",&c);
        flg[c]=1;
    }
    for(i=0;i<=101;i++){
        if(flg[i]==0){
            if(i<a&&min>a-i){
                min=a-i;
                num=i;
            }
            if(i>=a&&min>i-a){
                min=i-a;
                num=i;
            }
        }
    }
    printf("%d\n",num);
    return 0;
}