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>
using namespace std;
#define mod 1000000007
#define ll long long
#define mp make_pair
#define pb push_back
#define ff first
#define ss second
#define set0(a) memset ((a), 0 , sizeof(a))
#define set1(a) memset((a),-1,sizeof (a))
#define pi pair<int, int>
#define ps pair<string, string>
#define pl pair<long, long>
#define pll pair<long long, long long>
#define vll vector<long long>
#define vl vector<long>
#define vi vector<int>
#define vs vector<string>
#define vps vector< ps >
#define vpi vector< pi >
#define vpl vector< pl >
#define vpll vector< pll >
#define flash  ios_base::sync_with_stdio(false); cin.tie(NULL);
#define tc(t,T) for(long long t=0;t<T;t++)
#define rep(i,s,n,d) for(long long i=s;i<n;i=i+d)

bool sortbysec(const pll &a,
              const pll &b)
{
    return (a.second < b.second);
}
/*bool cxp pair<ll, pll> &a,
              const pair<ll, pll> &b)
{
    return (a.ff < b.ff);
}*/

void func(void)
{
        freopen("input.txt","r",stdin);
        freopen("output.txt","w",stdout);
}
ll gcd(ll a,ll b){
    if(b==0)return a;
    else return gcd(b,a%b);
}
void printStack(stack<string> s){
    if(s.empty())return;

    string x=s.top();
    s.pop();
    printStack(s);
    cout<<x;
    s.push(x);

}

int main(){
       ll x,n;
       cin>>x>>n;
       vi a(n);
       map<int,ll> m;
       rep(i,0,n,1)cin>>a[i],m[a[i]]++;
       if(m.find(x)==m.end()){
        cout<<x<<endl;
       }
       else{
           ll d=0;
           ll max1=x;
           for(int i=1;i<=100;i++){
                if(m.find(i)==m.end()){
                    ll s=abs(x-i);
                    if(max1>s){
                        max1=s;
                        d=i;
                    }
                    if(i>=x){
                        break;
                    }
                }
           }
           cout<<d<<endl;
       }

}


// 1 2 3 1 5 3 1 0 1 0 2
// 1 2 3 4 5 6 7 8 9 10 11