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>
#define rep(i,n) for(int i=0;i<n;i++)
using namespace std;

int x,n;
int p[110];
bool ans[110];
queue<int> que;

int near(int x){
  if(!ans[x-1])return x;
  if(x-1>0)que.push(x-1);
  if(x+1<=100)que.push(x+1);
  int next=que.front();
  que.pop();
  return near(next);
}

int main(){
  cin >> x >> n;

  if(n==0){
    cout << x << endl;
    return 0;
  }
  
  rep(i,n)cin >> p[i];
  memset(ans,false,sizeof(ans));
  rep(i,n)ans[p[i]-1]=true;

  cout << near(x) << endl;
  return 0;
}