struct BookMove
{
    uint64_t p1;
    uint64_t p2;
    int move;

    BookMove(uint64_t _p1, uint64_t _p2, int _move)
    {
        p1 = _p1;
        p2 = _p2;
        move = _move;
    };

    BookMove(uint64_t _p1, uint64_t _p2)
    {
        p1 = _p1;
        p2 = _p2;
    };
};

struct BookComparer {
public:
    bool operator()(const BookMove& b1, const BookMove& b2) const
    {
        return b1.p1 == b2.p1 && b1.p2 == b2.p2;
    }
};

struct BookHasher {
public:
    size_t operator()(const BookMove& b) const
    {
        return xorshift(b.p1) ^ b.p2;
    }
};

unordered_set<BookMove, BookHasher, BookComparer> openingBook;