C1 c1;
C2 c2;
C3 c3;
C4 c4;
D1 d1;
D2 d2;
D3 d3;
D4 d4;
E e;

class B<X, Y> {}

class C1<X extends X Function(Y), Y extends X Function(Y)> {}

class C2<X extends X Function(Y), Y extends Y Function(X)> {}

class C3<X extends X Function(X, Y), Y extends X Function(X, Y)> {}

class C4<X extends X Function(X, Y), Y extends Y Function(X, Y)> {}

class D1<X extends B<X, Y>, Y extends X Function(Y)> {}

class D2<X extends B<X, Y>, Y extends Y Function(X)> {}

class D3<X extends B<X, Y>, Y extends X Function(X, Y)> {}

class D4<X extends B<X, Y>, Y extends Y Function(X, Y)> {}

class E<X extends X Function(X)> {}

main() {}