#include<iostream>
#include<algorithm>
using namespace std;
int w,n,ans=0,l=1,r;
int a[30000+100];
int main(){
	freopen("group.in","r",stdin);
	freopen("group.out","w",stdin);
	cin>>w;
	cin>>n;
	for(int i=1;i<=n;i++)
	   cin>>a[i];
    sort(a+1,a+n+1);
    r=n;
    while(l<=r)
    {
    	if(a[l]+a[r]<=w){
		l++;r--;}
    	else r--;
    	ans++;
    }
    if(l==r)ans++;
    cout<<ans;
    fclose(stdin);
    fclose(stdout);
	return 0;
}