std::tuple<unsigned, unsigned> div(unsigned N, unsigned D) {
    unsigned Q = 0;
    unsigned R = 0;

    if(D != 0) {


    unsigned inv_N = 0;


    while(N > 0) {
        if(N % 2 == 1) {
            inv_N++;
        }
        inv_N <<= 1; // * 2
        N >>= 1; // / 2
    }
    inv_N = inv_N >> 1; // / 2

    while(inv_N > 0) {
        R <<= 1;

        if(inv_N % 2 == 1) {
            R++;
        }

        inv_N >>= 1;

        if(R >= D) {
            R = R - D;
            Q++;
        }
        Q <<= 1;
    }

    Q >>= 1;
    }

    return std::make_tuple(Q, R);
}