program cojs121;
var
  t,front,tail,ans,i,w,n:longint;
  a:array[1..30010]of longint;

procedure qsort(l,r:longint);
var
  i,j,x,t:longint;
begin
  randomize;
  i:=l; j:=r;
  x:=a[random(r-l+1)+l];
  repeat
    while a[i]<x do inc(i);
    while a[j]>x do dec(j);
    if i<=j then
    begin
      t:=a[i]; a[i]:=a[j]; a[j]:=t;
      inc(i); dec(j);
    end;
  until i>j;
  if i<r then qsort(i,r);
  if l<j then qsort(l,j);
end;

begin
assign(input,'group.in');reset(input);
assign(output,'group.out');rewrite(output);

  readln(w);
  readln(n);
  for i:=1 to n do
    readln(a[i]);
  qsort(1,n);
  front:=1; tail:=n; ans:=0;
  while front<=tail do
  begin
    t:=a[front]+a[tail];
    if t<=w then begin inc(front); dec(tail); inc(ans); end
    else begin dec(tail); inc(ans); end;
  end;
  writeln(ans);

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