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: Wrong Answer)

#include <bits/stdc++.h>
#include<unordered_map>
#include<unordered_set>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace __gnu_pbds;
using namespace std;

#define int long long
#define ff first
#define ss second
#define loop(i,k,n) for(int i=k;i<n;++i)
#define rloop(i,n,k) for(int i=n;i>=k;i--)
#define vi vector<int>
#define vvi vector<vector<int>>
#define vpii vector<pair<int,int>>
#define all(v) v.begin(),v.end()
#define mset(a,i) memset(a,i,sizeof(a))
#define mii map<int,int>  
#define pii pair<int,int>
#define deb(...) __f(#__VA_ARGS__, __VA_ARGS__)
#define mp make_pair
#define pb push_back
#define mod 1000000007  
#define endl "\n"
#define inf 1e18

typedef tree<int, null_type, less<int>, rb_tree_tag, tree_order_statistics_node_update> pbds;
typedef tree<pii, null_type, less<pii>, rb_tree_tag, tree_order_statistics_node_update> pbds1;

template <typename Arg1>
void __f (const char* name, Arg1&& arg1) { if(0) return; cout << name << " : " << arg1 << endl; }
template <typename Arg1, typename... Args>
void __f (const char* names, Arg1&& arg1, Args&&... args){   
    if(0) return; 
    const char* comma = strchr (names + 1, ',');
    cout.write (names, comma - names) << " : " << arg1 << " | "; __f (comma + 1, args...);
}
void get_it_done(){
    ios_base::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);
}
int gcd(int a,int b){
    if(b==0) return a;
    if(a<b) return gcd(b,a);
    return gcd(b,a%b);
}
const int N = 3e5+5;

void solve(){
    int x,n;
    cin>>x>>n;
    vi a(n);
    bool visited[105];
    loop(i,0,n) cin>>a[i],visited[a[i]] = 1;
    int num = -1;
    rloop(i,x,0){
        if(!visited[i]){
            num = i;
            break;
        }
    }
    loop(i,x,102){
        if(!visited[i]){
            if(abs(x-num)>abs(x-i)){
                num = i;
            }
            break;
        }
    }
    cout<<num<<endl;
    


}

int32_t main(){
    get_it_done(); 
    int tc=1;
    // cin >> tc;
    while (tc--){
        solve();        
    }
}