SELECT T1.name FROM Person AS T1 JOIN PersonFriend AS T2 ON T1.name  =  T2.name WHERE T2.friend IN (SELECT name FROM Person WHERE age  >  40) INTERSECT SELECT T1.name FROM Person AS T1 JOIN PersonFriend AS T2 ON T1.name  =  T2.name WHERE T2.friend IN (SELECT name FROM Person WHERE age  <  30)
Find the name of the person who has friends with age above 40 and under age 30?
[Schema (values) (types)]: | network_2 |  Person : name (text) , age (text) , city (number) , gender (text) , job (text) | PersonFriend : name (text) , friend (text) , year (number);