type point=^node;
     node=record
       data:string;
       last:integer;
       child:array [1..100] of point;
     end;

var head,headq,q:point;
    i,j,k,n,lasto:integer;
    s,v:string;
    visited:boolean;
    order:array [1..5000] of integer;

procedure init;
  var i:char;
begin
  lasto:=0;
  new(head); head^.last:=0; head^.data:='';
end;

procedure add(p:point);
  var i:integer;
      same:boolean;
begin
  if p^.data=headq^.data then begin

    if headq^.last<>0 then begin

      same:=false;

      for i:=1 to p^.last do
        if p^.child[i]^.data=headq^.child[1]^.data then begin
          same:=true;
          break;
        end;

      if same then begin
        headq:=headq^.child[1];
        add(p^.child[i]);
      end
      else begin
        p^.last:=p^.last+1;
        p^.child[p^.last]:=headq^.child[1];
      end;

    end;

    visited:=true;

  end;
  for i:=1 to p^.last do add(p^.child[i]);
end;

procedure print(p:point; k:integer);
  var i,j:integer;
        s:point;
begin

  for i:=1 to k do write(' ');

  for i:=1 to p^.last-1 do
    for j:=i+1 to p^.last do
      if p^.child[i]^.data>p^.child[j]^.data then begin
        s:=p^.child[i];
        p^.child[i]:=p^.child[j];
        p^.child[j]:=s;
      end;

  if p^.data<>'' then writeln(p^.data);

  for i:=1 to p^.last do print(p^.child[i],k+1);
end;

begin

  init;
  readln(n);

  for i:=1 to n do begin

    readln(s); v:='';
    new(headq); headq^.last:=0; q:=headq;

    for j:=1 to length(s) do begin
      if s[j]<>'\' then v:=v+s[j]
         else begin
           q^.data:=v;
           q^.last:=1;
           new(q^.child[1]); q:=q^.child[1];
           v:='';
         end;
    end;

    q^.last:=0;  q^.data:=v;
    visited:=false;
    add(head);

    if not visited then begin

       head^.last:=head^.last+1;
       head^.child[head^.last]:=headq;
       k:=0;

       for j:=1 to lasto do
         if head^.child[order[j]]^.data>headq^.data then begin
           for k:=lasto+1 downto j+1 do order[k]:=order[k-1];
           order[j]:=head^.last;
           break;
         end;

       lasto:=lasto+1;
       if lasto=1 then order[lasto]:=head^.last;

    end;
  end;

  print(head,-1);

end.

You didn't manage well those chained lists, there are points who do
not have a child, nor a reference to nil