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: Accepted)

/***************************************** START OF TEMPLATE *********************************************/

#include<bits/stdc++.h>

using namespace std;

#define  SPEED          ios:: sync_with_stdio(0);cin.tie(0);cout.tie(0);cout<<fixed;cout<<setprecision(10);
#define  randomINIT     mt19937 rnd(chrono::steady_clock::now().time_since_epoch().count());
#define  foo(i,a,n)     for(ll i = (a); i <= n; i++)
#define  frr(i,a,n)     for(ll i = (a); i >= n; i--)
#define  fo(i,n)        for(ll i = 0; i < n; i++)
#define  newl           cout<<"\n";
#define  f              first
#define  s              second
#define  pb             push_back
#define  mp             make_pair
#define  sym(s)         s="#"+s+"#";   
#define  all(x)         (x).begin(),(x).end()
#define  alll(x, n)     x+1, x+n+1
#define  mset(x,val)    memset(x,val,sizeof(x))
#define  mset1d(a,n,v)  foo(i,0,n+5)a[i]=v;
#define  mset2d(a,n,m,v)foo(i,0,n+5)foo(j,0,m+5)a[i][j]=v;
#define  INP(a,n)       foo(i,1,n) cin>>a[i];
#define  deb1d(a,n)     foo(i,1,n)cout<<a[i]<<" ";newl;
#define  deb2d(a,n,m)   foo(i,1,n){foo(j,1,m){cout<<a[i][j]<<" ";}newl;}    
#define  debm(a)        for(auto it: a)cout<<"{"<<it.f<<","<<it.s<<"}, ";newl;
#define  debp(a,n)      foo(i,1,n)cout<<"{"<<a[i].f<<","<<a[i].s<<"}, ";newl;
#define  debv(a)        for(auto it: a)cout<<it<<" ";newl;
#define  deb1(a)        cout<<a<<" ";newl;
#define  deb2(a,b)      cout<<a<<" "<<b<<" ";newl;
#define  deb3(a,b,c)    cout<<a<<" "<<b<<" "<<c<<" ";newl;
#define  deb4(a,b,c,d)  cout<<a<<" "<<b<<" "<<c<<" "<<d;newl;
#define  ll             long long
#define  ld             long double
#define  pll            pair<ll,ll>
#define  vll            vector<ll>
#define  vpll           vector<pll>

const ld   PI    =  3.14159265358979323846; 
const ll   MOD   =  1e+9+7;
const ll   INF   =  LLONG_MAX;
const int  INFi  =  INT_MAX;
const ll   N     =  2e+5+8;

vll adj[N]; ll vis[N];
ll dx4[]={0,1,0,-1}, dy4[]={1,0,-1,0};

ll test_cases = 1; randomINIT;

/*********************************************************************************************************/
/***************************************** VARIABLE DECLARATIONS *****************************************/
ll n, x, a[N];


/***************************************** FUNCTION IMPLEMENTATIONS **************************************/



/***************************************** START OF MAIN FUNCTION ****************************************/
void MAIN(ll tc){
    cin>>x>>n;
    foo(i,1,n){
        cin>>a[i];
        vis[a[i]]=1;
    }
    ll res =INF, ans=INF;
    foo(i,-100,200){
        if(vis[i]==0) 
            res=min(res, abs(x-i));
    }
    foo(i,-100,200){
        if(vis[i]==0 && abs(x-i)==res){
            cout<<i;
            break;
        }
    }


}

int main(){
    SPEED;

    //cin>>test_cases;
    foo(i,1,test_cases){
        MAIN(i);
    }
}