#include <cstdio>
#include <algorithm>
using namespace std;
int w,n,a[30005],ans;
bool comp(int x,int y){return x>y;}
int main()
{
	freopen("group.in","r",stdin);
	freopen("group.out","w",stdin);
	scanf("%d%d",&w,&n);
	for(int i=1;i<=n;i++)
		scanf("%d",&a[i]);
	sort(a+1,a+n+1,comp);
	int head=1,tail=n;
	while(tail>head)
	{
		if(a[head]+a[tail]<=w)
		{
			ans++;
			head++;
			tail--;
		}
		else
		{
			ans++;
			head++;
		}
	}
	if(head==tail) ans++;
	printf("%d",ans);
	return 0;
}