#include<bits/stdc++.h>
using namespace std;
int a[50010] = {};
int maxn = 0;
int ab(int a)
{
	if(a<0)a*=-1;
	return a;
}
int main()
{
	int t,n;
	cin>>t>>n;
	for(int i = 1;i<=n;i++)cin>>a[i];
	sort(a+1,a+n+1);
	for(int i = 1;i<=n;i++)
	{
		int b = a[i]+t-ab(a[i]);
		int x = upper_bound(a+i+1,a+n+1,b)-a-1;
		maxn = max(maxn,x-b+1);
	} 
	cout<<maxn;
}