class List<A> { A a = null; } class Vektor<A> extends List<A> { A a = null; } class Stack<A> extends Vektor<A> { A a = null; } class ClassB<A, B, C> { A a = null; B b = null; C c = null; } class ClassA<A, B, C> extends ClassB<C, B, A> { A a = null; B b = null; C c = null; } class Int { } class Bool { } class otth15 { void f1( X<A> a ) { } }