rsize_t
char *gets_s(char *, rsize_t);
typedef size_t rsize_t;
errno_t memset_s(void *, rsize_t, int, rsize_t);
_gets_s(char *buf, rsize_t n)
gets_s(char *buf, rsize_t n)
memset_s(void *s, rsize_t smax, int c, rsize_t n)
rsize_t lim;