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;

typedef long long int li;
typedef long double ld;
typedef vector<li> vi;
typedef pair<li,li> pi;
#define PB push_back
#define MP make_pair
#define F first
#define S second
#define B begin()
#define E end()
#define f(i,l,r) for(li i=l;i<=r;++i)
#define fr(i,l,r) for(li i=l;i>=r;--i)
#define u_map unordered_map
#define endl "\n"
#define debug(x) cout<<#x<<" = "<<x<<endl;

li fastpow(li base,li exp,li M) 
{
    li res=1;
    while(exp>0) {
        if(exp&1)
            res=(res*base)%M;

        base=(base*base)%M;
        exp>>=1;
    }
    return res;
}

void solve()
{
    li x,n;
    cin>>x>>n;

    li a[n];

    f(i,0,n-1)
    {
        cin>>a[i];
    }   

    li mn=1e18;

    li ans=100;

    f(i,0,n-1)
    {
        if(abs(a[i]-x)<=mn)
        {
            mn=abs(a[i]-x);
            ans=min(ans,a[i]);
        }
    }

    cout<<ans;
}

int main()
{    
    

    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    cout.tie(NULL);

    li t=1;

    // cin>>t;

    while(t--)
    {
        solve();
    }

    return 0;
}