[$s]-[$S]-[$s]-[$S]- [7s]-[7D] f 7 D 7 S [3s]-[3S]-[3s]-[3S]- [!s]-[!S] f ! D ! S [$s]-[$S]-[$s]-[$S]- [7s]-[7D] f 7 D 7 S [3s]-[3S]-[3s]-[3S]- [!f]---- !-H-H-H- [QH]-Q S Q D [Qf] G [7H] H 7 G 7 f [7D] f [0G]-0 a 0 S [0D] f [*G] G * f * f [*f] S [Qf]-Q p Q-Q- [7f] f 7 D 7 f [7D] S [0S] a 0-0-0