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 <bits/stdc++.h>
using namespace std;
int a[105],n;
bool esta(int k){
    bool b=true;
    for(int i=0;i<n;i++){
        if(k==a[i]) b=false;
    }
    if(b) return true;
    else return false;
}

int main() {
    int x;
    cin>>x>>n;
    for(int i=0;i<n;i++){
        cin>>a[i];
    }
    int t1=1e5,t2=1e5;
    for(int i=0;i<=200;i++){
        if(esta(i)){
            if(x>i) t1=min(t1,x-i);
            else t2=min(t2,i-x);
        }
    }
    if(t1>t2) cout<<x+t2<<"\n";
    else cout<<x-t1<<"\n";
    
	return 0;
}