#include <iostream>
#include <cstdio>
#include <cstring>
#include <cmath>
#include <algorithm>
int n,m,c,p;
const int maxn=10000+10;
int a[maxn];
int min1=1000000;
using namespace std;
int main()
{
	//freopen("test.in","r",stdin);
	//freopen("test.out","w",stdout);
	freopen("teststr.in","r",stdin);
	freopen("teststr.out","w",stdout);
	
	cin>>m>>n;
	for(int i=0;i<n;i++)
	{
		cin>>a[i];
	}
	p=m/2;
	
	for(int i=0;i<n;i++)
	{
		if(fabs(a[i]-p)<min1)
		{
			min1=fabs(a[i]-p);
			c=i;
		}
	}
	if(a[c]>p) cout<<p;
	else cout<<a[c];
	cout<<endl;
	return 0;
}