please gime some contrtests...

VAR
 ok : BooLean;
 N, M : integer;
 B : Array [1 .. 100] of integer;
 A : Array [1 .. 100, 1 .. 100] of integer;

PROCEDURE In_Data;
 Var
  i, W : integer;
   Begin
    ReadLn(N);
    ok := false;
     for i := 1 to N do
      begin
       Read(W);
        if W = 0 then
          begin
           ok := true;
           Exit;
          end;
       while W <> 0 do
        begin
         A[i, W] := 1;
         Read(W);
        end;
       ReadLn;
      end;
   End;

PROCEDURE Out_Data;
 Var
  i : integer;
   Begin
    WriteLn(M);
     for i := 1 to N do
      if B[i] = 1 then
        Write(i, ' ');
   End;

PROCEDURE Solve;
 Var
  i, j : integer;
   Begin
    for i := 1 to N do
     begin
      if B[i] = 0 then
        B[i] := 1;
      for j := 1 to N do
       if A[i, j] = 1 then
         begin
          if B[i] = 1 then
            B[j] := 2
              else
            B[j] := 1;
          A[i, j] := 0;
          A[j, i] := 0;
         end;
     end;
    M := 0;
    for i := 1 to N do
     if B[i] = 1 then
       inc(M);
   End;

PROCEDURE Run;
   Begin
    In_Data;
     if ok then
       begin
        WriteLn(0);
        Exit;
       end;
     Solve;
     Out_Data;
   End;

BEGIN
 Run;
END.