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: Runtime Error)

#include<bits/stdc++.h>
using namespace std;
#define ll unsigned long long
#define mod 1000000009

int main(){
  ios_base::sync_with_stdio(0);
  int t=1;  
  //cin>>t;
  while(t--){
    int n,x;
    cin>>x>>n;
    set<int> s;
    for(int i=1; i<=100; i++) s.insert(i);
    for(int i=0; i<n; i++){
      int temp;
      cin>>temp;
      s.erase(temp);
    }
    set<int>::iterator it = lower_bound(s.begin(), s.end(), x);
    int ans1 = *it;
    it--;
    int ans2 = *it;
    if(abs(ans2-x)<=(ans1-x)) cout<<ans2;
    else cout<<ans1;
    

    }
    return 0;
}