What are the names of all of Alice's friends of friends?
select distinct t4.name from personfriend as t1 join person as t2 on t1.name = t2.name join personfriend as t3 on t1.friend = t3.name join personfriend as t4 on t3.friend = t4.name where t2.name = 'Alice' and t4.name != 'Alice'