program cojs121;
const
  maxn=30000;
var
  a:array[1..maxn] of integer;
  i,n,max,ans,fr,ta:longint;
procedure qp(l,r:longint);
var
  i,j,x,y:longint;
begin
  randomize;
  x:=a[random(r-l+1)+l];
  i:=l;j:=r;
  repeat
    while a[i]<x do inc(i);
	while a[j]>x do dec(j);
    if i<=j then
	  begin
	    y:=a[i]; a[i]:=a[j]; a[j]:=y;
		inc(i); dec(j);
	  end;
  until i>j;
  if j>l then qp(l,j);
  if i<r then qp(i,r);
end;
begin
  assign(input,'group.in');
  assign(output,'group.out');
  reset(input);
  rewrite(output);

  readln(max);
  readln(n);
  for i:=1 to n do
    readln(a[i]);
  qp(1,n);
  fr:=1; ta:=n;
  while fr<ta do
	if a[fr]+a[ta]<=max then
	  begin
	    inc(fr);dec(ta);inc(ans);
	  end
	else
      begin
	    dec(ta); inc(ans);
	  end;
  if ta=fr then
    inc(ans);
  writeln(ans);

  close(input);
  close(output);
end.