#include<algorithm>
#include<cstdio>
using namespace std;

int n,k;
int tot=0;
int head=0,tail=0;
int h[30001]={0};

void work();
int main()
{
	freopen("group.in","r",stdin);
	freopen("group.out","w",stdout);
	work();
	return 0;
}

void work()
{
	scanf("%d%d",&k,&n);
	for(int i=1;i<=n;++i)
	{
		scanf("%d",&h[i]);
	}
	sort(h+1,h+n+1);
	head=1;
	tail=n;
	while(head<=tail)
	{
		if(head==tail)
		{
			tot++;
			break;
		}
		if(h[head]+h[tail]<=k)
		{
			head++;
			tail--;
			tot++;
		}
		else
		{
			tail--;
			tot++;
		}
	}
	printf("%d",tot);
}