program cogs121;
const
   maxn=30000;
var
  n,i,j,w,total:longint;
  a:array[1..maxn] of longint;
procedure kp(l,r:longint);
var
   i,j,x,t:longint;
begin
   i:=l; j:=r;
   x:=a[(l+r) div 2];
   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 kp(i,r);
   if j>l then kp(l,j);
end;
begin
   assign(input,'group.in'); reset(input);
   assign(output,'group.out'); rewrite(output);
   total:=0;
    readln(w);
    readln(n);
    for i:=1 to n do readln(a[i]);
    kp(1,n);
    i:=1;
    while i<=n do
      begin
        if i<>n then
         begin
        if (a[i]+a[i+1])<=w then begin inc(total); inc(i,2); end else
        begin
         inc(total);
         inc(i);
        end;
         end else begin inc(total); inc(i); end;
      end;
   writeln(total-1);

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