#define NLEN 30
struct book
{
        int isbn;
        char name[NLEN];
        char auther[NLEN];
        char publisher[NLEN];
        struct user *hasMe;

        struct book *left;
        struct book *right;
};

struct user
{
        int id;
        char name[NLEN];
        char address[NLEN];
        struct book *borrowed;

        struct user *next;
        struct user *prev;
};
int main()
{}