12 times 7 t7 w$ f3 L$ T% }3 R( ]$ k, f公仔箱論壇$ C' p4 ^8 a1 s* i
each time 4 person but 1 need to back to pick up the other 3 0 A$ H9 a2 t, e3 L; Qreturn x 10 = 30 people & ^0 F& ]0 v/ P y8 w' i1 time return 8 J4 [6 ]& w+ A( o, c2 o' S+ s2 person on last time 4 F9 V9 z$ u9 E( l( W3 C( L
total : 12 times