t t 1 | t 1 | t t2 t1 |1 t1 3 5 1 |4 t t t3 5 2 3 2 3 | t | t | 1 t t t t t t t t t | t t t t t | t t t t t t D 7 ? D ? D ? D?D ?D? 2 4 5 3 3 5 1 t 2 to t t t t t 1 I t1 t t t t | t 1 I t | t 4 3 2 t t t | t 3 t | | t t t t t t t t t t t t t t t t | | t t t D ? ? ? D ?