#define MAX 50
        
typedef struct NodeTag {
        int ID;
        char firstname[MAX];
        char lastname[MAX];
        char studentgender[MAX];
        struct NodeTag *next;
} Structure;
         
extern Structure *add_node (Structure *);
extern int find_id (Structure *, int, Structure **, Structure **);
extern void delete_node (Structure **, Structure *, Structure *);
extern void display_name (Structure *);
extern void delete_list (Structure **);