var
  b:array[1..30000]of boolean;
  a:array[1..30000]of longint;
  zong,n,m,i,t:longint;
procedure qsort(l,r:longint);
var
  i,j,x,y:longint;
begin
  i:=l;j:=r;x:=a[(l+r) div 2];
  repeat
    while a[i]<x do inc(i);
    while x<a[j] do dec(j);
    if not(i>j) then
    begin
      y:=a[i];a[i]:=a[j];a[j]:=y;
      inc(i);j:=j-1;
    end;
  until i>j;
  if l<j then qsort(l,j);
  if i<r then qsort(i,r);
end;
begin
  assign(input,'group.in');reset(input);
  assign(output,'group.out');rewrite(output);
  read(m,n);zong:=0;
  for i:=1 to n do read(a[i]);
  qsort(1,n);fillchar(b,sizeof(b),true);
  for i:=1 to n do
  if b[i]=true then
  begin
    b[i]:=false;t:=i;
    while (t+1<=n) and (a[t+1]+a[i]<=m) and (b[t+1]=true) do t:=t+1;
    b[t]:=false;zong:=zong+1;
  end;
  writeln(zong);
  close(input);close(output);
end.