Consider the following structure declaration:

This declaration illustrates that one structure can be embedded within another, just as arrays can be embedded within structures and arrays can be embedded within arrays.
The following procedure (with some expressions omitted) operates on this structure:

On the basis of this information, fill in the missing expressions in the code  for st_init.

struct test { short *p; struct { }; short x; short y; } s; struct test *next;