I think that following two input routines are the same:
#1, gets AC
-------------------------
ReadLn(N);
For I := 1 To N Do
 begin
  For J := 1 To N Do
   begin
    Read(Ch);
    <work>
   end;
  ReadLn;
 end;
----------------------
#2, gets WA on test 4
----------------------
Read(N);
Read(Ch);
For I := 1 To N Do
 For J := 1 To N Do
  begin
   While Not((Ch = 's')Or(Ch = 'S')) Do Read(Ch);
   <work>
   Read(Ch);
  end;
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Where am I mistake?