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;
typedef long long ll;

int main()
{
    int x, n;
    cin >> x >> n;
    if (n == 0)
    {
        cout << x << endl;
    }
    else
    {
        vector<int> p;
        vector<int> ans;
        int ans1=1000,ans2=1000;
        for (int i = 0; i < n; i++)
        {
            int a;
            cin >> a;
            p.push_back(a);
        }
        for(int i=x;;i--){
            bool flag=true;
            for(int j=0;j<n;j++){
                if(p[j]==i){
                    flag=false;
                }
            }
            if(flag==true){
                ans1=i;break;
            }
        }
        for(int i=x;;i++){
            bool flag=true;
            for(int j=0;j<n;j++){
                if(p[j]==i){
                    flag=false;
                }
            }
            if(flag==true){
                ans2=i;break;
            }
        }
        cout<<((abs(ans1-x)<=abs(ans2-x))?ans1:ans2)<<endl;
    }
}