12 times + t+ G5 Y3 b% R' N8 } f3 \3 ^: n) g3 l: g
each time 4 person but 1 need to back to pick up the other 3" u: g& p" M( G; T8 a3 f
return x 10 = 30 people7 h3 d a- j/ s7 |5 C9 y" W
1 time return: J2 H, r! Y( \4 U& |
2 person on last time tvb now,tvbnow,bttvb( }" g9 a4 t* L# j% n
total : 12 times