What's the test 15?Can somebody tell me?
    Thank you.
    Here is my code with O(N) soulution which is get WA on #15
program coats;
const
  maxn=200100;
var
  g,next,t:array [0..maxn] of int64;
  l,a:array [0..maxn] of int64;
  i,k,m,n:longint;
  r:int64;
procedure init;
  begin
    read(n,r);
    for i:=1 to n do read(a[i]);
  end;
procedure solve;
  begin
    m:=1;k:=1;
    next[n]:=g[1];g[1]:=n;l[1]:=a[n];t[1]:=1;
    for i:=n-1 downto 1 do
      begin
        if l[k]-a[i]>r
          then begin
                 next[i]:=g[k];g[k]:=i;l[k]:=a[i];inc(t[k]);
                 inc(k);if k>m then k:=1;
                 continue;
               end;
        inc(m);next[i]:=g[m];g[m]:=i;l[m]:=a[i];t[m]:=1;
      end;
    writeln(m);
    for i:=m downto 1 do
      begin
        write(t[i]);
        r:=g[i];
        while r<>0 do
          begin
            write(' ',r);
            r:=next[r];
          end;
        writeln;
      end;
  end;
begin
  assign(input,'coats.in');reset(input);
  assign(output,'coats.out');rewrite(output);
  init;
  solve;
  close(input);close(output);
end.

    Please help!

   Nothing serious.Just a big and hidden mistake in my program.
   Thank you anyway.