prog;

begin
  var a : string;
  var b : "hello";
  var c : string

  a := "ha";
  c := "he";

  write "ha" <> a;
  write a <> "ha";
  write b <> a;
  write a <> b;
  write a <> c;
  write c <> a;
  write a <> a;

end;
end prog