SOS!!!Why I got WA.This is my program:

const
  MAX = 20;
var
  List : array [0 .. 9, 1 .. MAX] of shortint;
  Num : array [1 .. MAX, 1 .. 2] of shortint;
  s : set of 1 .. MAX;
  i, j, t, n : longint;
  c : char;
  b : boolean;
Procedure Out;
  var
    oi, oj : integer;
  begin
    for oi := t downto 1 do
      for oj := 1 to t do
        begin
          if Num [oj, 2] = oi
            then write (Num [oj, 1]);
        end;
    writeln;
  end;
Procedure Search (st, ss : longint);
  var
    sf, sa, si : longint;
  begin
    if Num [st, 1] >0
      then sf := t
      else sf := t - 1;
    for si := 1 to sf do
      if (not (si in s)) and b
        then
        begin
          s := s + [si];
          Num [st, 2] := si;
          sa := List [Num [st, 1], si];
          if st < t
            then Search (st + 1, (ss + sa) mod 7);
          if (st = t) and ((ss + sa) mod 7 = 0)
            then begin
                   Out;
                   b := false;
                 end;
          s := s - [si];
        end;
  end;
begin
  for i := 0 to 9 do
    begin
      t := i mod 7;
      List [i, 1] := t;
      for j := 2 to 20 do
        begin
          t := (t * 10) mod 7;
          List [i, j] := t;
        end;
    end;
  readln (n);
  for i := 1 to n do;
    begin
      b := true;
      s := [];
      t := 0;
      read(c);
      while c in ['0' .. '9'] do
        begin
          t := t + 1;
          Num [t, 1] := ord (c) - 48;
          read (c);
        end;
      Search (1, 0);
    end;
end.