struct A {
   int a;
   struct A *next;
};

struct B {
   int b;
   struct B *next;
};

struct C {
   int c;
   struct C *next;
};

struct D {
   A *a;
   B *b;
   C *c;
   struct D *next;
};

struct E {
   char *name;
   struct E *next;
};

struct F {
   D *d;
   E *e;
   struct F *next;
};