Amr live Lala Land Lala Land beautiful country locate coordinate line Lala Land famous apple tree grow everywherelala land exactly n apple tree tree number locate position xi ai apple grow Amr want collect apple apple tree Amr currently stand x0 position at begin choose right leave Hell continue direction meet apple tree do not visit Hell apple reverse direction continue walk direction meet apple tree do not visit in word Amr reverse direction visit new apple tree Amr stop collect apple tree do not visit direction facingwhat maximum number apple collect