/*
After test, there is bug for value -2147483648 (the minimus integer);
as for integer -(-2147483648) is still -2147483648, not 2147483648.
So we need a larger type which could contains value 2147483648
typedef long long_int;

if the sizeof(long) is equal to sizeof(int) in some system,
you may need to use long long instead

typedef long long long_int;

 */

public class MathOps {

    public static int add(int x, int y) {

        if (y == 0) return x;
        int a = x ^ y;        // add
        int b = (x & y)  e * y) {
            y = (x / y + y) / 2.0;
        }
        return y;
    }

    public static double pow(double x, int y) {
        if (y == 0) return 1;
        if (y == 1) return x;

        boolean negative = false;
        if (y < 0) {
            negative = true;
            y = -y;
        }

        double r = pow(x, y / 2);
        r = r * r;

        if (y % 2 != 0) r = r * x;
        if (negative) r = 1 / r;

        return r;
    }

    public static int divide(int dividend, int divisor) {

        if (divisor == 0)
            throw new ArithmeticException("divisor is 0");

        boolean neg_dividend = (dividend < 0);
        boolean neg_divisor = (divisor < 0);

        if (neg_dividend)
            dividend = (dividend ^ -1) + 1;
        if (neg_divisor)
            divisor = (divisor ^ -1) + 1;

        int result = 0;

        while (dividend >= divisor) {
            dividend -= divisor;
            result++;
        }

        if (neg_dividend ^ neg_divisor)
            result = (result ^ -1) + 1;

        return result;

    }

    public static int divide1(int dividend, int divisor) {
        assert (divisor != 0);

        boolean bNeg = false;

        if ((dividend < 0 && divisor > 0) || (dividend > 0 && divisor < 0))
            bNeg = true;

        long la = dividend;
        long ula = la < 0 ? -la : la;
        long lb = divisor;
        long ulb = lb < 0 ? -lb : lb;

        int msb = 0;
        while ((ulb = 0; i--) {
            if ((ulb  ula) continue;
            q |= (1