#define SIZE 100

struct Reader
{
    int id;
    char name[SIZE], surname[SIZE];
    int age;
};

struct Book
{
    int id;
    char title[SIZE], author[SIZE];
    int year;
};

struct CheckOut
{
    int id;
    struct Date
    {
        int day, month, year;
    };
    int reader_id, book_id;
};