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)

// //code by smigwump
// //https://codeforces.com/blog/entry/62393
// #include <bits/stdc++.h>
// #define PB push_back
// #define MP make_pair
// #define F first
// #define S second
// #define REP(i,a,b) for(int i = a; i <= b; i++)

// typedef long long ll;

// using namespace std;

// int main() {
//     // #ifndef ONLINE_JUDGE
//     //     freopen("input.txt", "r", stdin);
//     //     freopen("output.txt", "w", stdout);
//     // #endif

//     ios_base::sync_with_stdio(false);
//     cin.tie(NULL);
//     int x,n;
//     cin>>x>>n;
//     bool flag=0;
//     if(n==0) {
//         cout<<x;
//     } 
//     else {    
//     vector<int> p(n,0);
//     REP(i,0,n-1) cin>>p[i];
//     sort(p.begin(),p.end());
//     vector<int> pp;
//     REP(i,1,p[0]-1) {
//         pp.PB(i);
//         //cout<<"done";
//     }
//     if(p[0]==x) {
//         flag=1;
//         pp.PB(x);
//     }
//     REP(i,1,n-1) {
//         REP(j,p[i-1]+1,p[i]-1) {
//             pp.PB(j);
//             //cout<<"fone";
//         }
//         if(p[i]==x) {
//             flag=1;
//             pp.PB(x);
//         }
//     }
//     REP(i,p[n-1]+1,100) {
//         pp.PB(i);
//         //cout<<"gone";
//     }
//     sort(pp.begin(),pp.end());
//     // cout<<"\n\n";
//     // for(auto v:pp) {
//     //     cout<<v<<"\t";
//     // }
//     // cout<<"\n";
//     REP(i,0,pp.size()-1) {
//         if(pp[i]==x) {
//             if(!flag) {
//                 cout<<x;
//             }
//             else {            
//                 if(i==0) {
//                     cout<<pp[1];
//                 }
//                 else if(i==(pp.size()-1)) {
//                     cout<<pp[pp.size()-2];
//                 }
//                 else {
//                     int t1 = pp[i+1];
//                     int t2 = pp[i-1];
//                     //cout<<t1<<"boom"<<t2<<"zoom";
//                     if((t1-x)<(x-t2)) {
//                         cout<<t1;
//                     }
//                     else {
//                         cout<<t2;
//                     }
//                 }
//             }
//         }
//     }
// }
//     return 0;
// }

//code by smigwump
//https://codeforces.com/blog/entry/62393
#include <bits/stdc++.h>
typedef long long ll;
#define PB push_back
#define MP make_pair
#define F first
#define S second
#define REP(i,a,b) for(ll i = a; i <= b; i++)

using namespace std;

int main() {
    // #ifndef ONLINE_JUDGE
    //     freopen("input.txt", "r", stdin);
    //     freopen("output.txt", "w", stdout);
    // #endif

    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    ll x,n;
    cin>>x>>n;
    if(n==0) {
        cout<<x;
    }
    else {
        vector<ll> p(n);
        bool flag = 0;
        ll itr = 0;
        REP(i,0,n-1) {
            cin>>p[i];
            if(p[i]==x) {
                itr = i;
                flag = 1;
            }
        }
        if(!flag) {
            cout<<x;
        }
        else {
            
        }
    }
    return 0;
}