int sk_insert(STACK *sk,char *data,int where);
char *sk_delete(STACK *st,int loc);
char *sk_delete_ptr(STACK *st, char *p);
int sk_find(STACK *st,char *data);
int sk_insert(STACK *sk,char *data,int where);
char *sk_delete(STACK *st,int loc);
char *sk_delete_ptr(STACK *st, char *p);
int sk_find(STACK *st,char *data);