void benchmark(void)
{
    unsigned long int re = 0, wyn = 0, re2 = 0, re3 = 0;
    unsigned long int an[33];
    unsigned long int bn[33];
    unsigned long int ds[2];

    uint64_t dist = 0, now = 0;
    double temp1 = 0;

    unsigned long int wn[33];
    unsigned long int aa = 0, bb = 0, cc = 0, dd = 0;
    mpz_t n,start,end,remainder,currentNumber, qu, mul, res, b1, b2, wyn1, wyn2, result;
    mpz_t n2;
    size_t a = 0, b=0, w=0, d=0;

    mpz_init_set_str(n, "B98E7F4EE7C2FA971E4807B619133C2859ECD24FEDE69CC6C096E7701C77F07C24FAC4C39B40C159CF8C8F9981C2FFD00C862359BC43592FA9B8591967EE0EC5C9EE401F69249610EEB7DCA96644ABB8E16AABEAC64FCF0A5140529F0B220E3C68097E28B6BCC96C3F778A8DA5582CF6AE7CFEC62612E1AFCE462CF0A1396A7F", 16);
    mpz_init(qu);
    mpz_init(res);
    mpz_init(start);
    mpz_sqrt(start, n);
    mpz_out_str(stderr, 16, start);
    mpz_init(end);
    mpz_init_set_ui(result, 0);

    mpz_init(wyn1);
    mpz_init(wyn2);

    mpz_add_ui(end, start, 1000000000);

    mpz_add_ui(end, end, 1000000000);
    mpz_add_ui(end, end, 1000000000);
    mpz_add_ui(end, end, 1000000000);
    mpz_add_ui(end, end, 1000000000);
    mpz_add_ui(end, end, 1000000000);
    mpz_add_ui(end, end, 1000000000);
    mpz_add_ui(end, end, 1000000000);
    mpz_add_ui(end, end, 1000000000);
    mpz_add_ui(end, end, 1000000000);

    mpz_init2(remainder, 1024);
    mpz_init2(mul, 1024);
    mpz_init_set(currentNumber, start);

    mpz_init2(n2, 1024);

    mpz_init(b1);
    mpz_init(b2);

    if(mpz_even_p(currentNumber))
        mpz_sub_ui(currentNumber, currentNumber, 1);

    fprintf(stderr, "RSA: Starting Benchmark.\n");
    counter.Start();

    mpz_cdiv_qr(qu, remainder, n, currentNumber);
    mpz_set(wyn1, remainder);
    if(mpz_cmp_ui(remainder, 0) == 0)
    {
        mpz_set(result, currentNumber);
        fprintf(stderr, "RSA: ending, found a result.\n");
    }

    mpz_add_ui(currentNumber, currentNumber, 2);
    now += 2;
    mpz_sub_ui(qu, qu, 2);

    mpz_export(wn, &w, 1, 4, 0, 0, n);
    wyn = wn[w-1];
    wyn = wyn & 0xFFFF;

    /*
    test this optimization for correct results
    simple school mul is
        AB
        CD
    _______
        BD
       AD
       CB
  +   AC

    So last bit (D) are always same after first mul. To be sure in 110% we check only last 16 bits.
    */
/*
    mpz_init_set(n1, start);

    mpz_mul(n2, n1, n1);
    mpz_export(wn, &w, 1, 4, 0, 0, n2);
    wyn = wn[w-1];
    wyn = wyn & 0xFFFF;

    mpz_export(an, &a, 1, 4, 0, 0, n1);
    mpz_export(bn, &b, 1, 4, 0, 0, n1);
    re = (an[a-1] * bn[b-1]) & 0xFFFF;*/

    mpz_export(an, &a, 1, 4, 0, 0, qu);
    mpz_export(bn, &b, 1, 4, 0, 0, currentNumber);

    aa = an[a-1];
    bb = bn[b-1];


    //dist
    mpz_sub(res, end, start);
    temp1 = mpz_get_d(res);
    dist = (uint64_t)temp1;

    while (now < dist)
    {
        //mpz_export(an, &a, 1, 4, 0, 0, qu);
        //mpz_export(bn, &b, 1, 4, 0, 0, currentNumber);

        //mul 32x32 bit
        //check last 16 bits
        //re = (an[a-1] * bn[b-1]) & 0xFFFF;
        re2 = (aa * bb) & 0xFFFF;

        //if(re != re2)
        //  printf("Ups...\n");

        if((re2 ^ wyn) == 0)
        {
            ds[1] = now & 0xFFFFFFFF;
            ds[0] = now >> 32;
            mpz_import (res, 2, 1, sizeof(ds[0]), 0, 0, ds);

            mpz_sub(qu, qu, res);
            mpz_add(currentNumber, currentNumber, res);

            mpz_mul(mul, qu, currentNumber);
            if(mpz_cmp(mul, n) == 0)
            {
                fprintf(stderr, "RSA: ending, found a result.\n");
                mpz_set(result, currentNumber);
            }
        }

        aa -= 2;
        bb += 2;
        now += 2;

        //mpz_sub_ui(qu, qu, 2);
        //mpz_add_ui(currentNumber, currentNumber, 2);
    }

    mpz_clear(n);
    mpz_clear(start);
    mpz_clear(end);
    mpz_clear(remainder);
    mpz_clear(currentNumber);
}