public class LameMath {
    public static int sum(int x, int y) {
	return x + y;
    }

    public static int diff(int x, int y) {
	return x - y;
    }

    public static int prod(int x, int y) {
	return x * y;
    }

    public static int quot(int x, int y) {
	return x / y;
    }

    public static boolean isEven(int x) {
	return x % 2 == 0;
    }
	
    public static boolean addWorks() {
	int expectedSum = 10;
	int actualSum = sum(2, 8);

	System.out.print("sum(2, 8): ");
	if (expectedSum != actualSum) {
	    System.out.println("error: expected " + expectedSum + ", but found " + actualSum);
	    return false;
	} else {
	    System.out.println("ok");
	}

	expectedSum = -10;
	actualSum = sum(-2, -8);

	System.out.print("sum(-2, -8): ");
	if (expectedSum != actualSum) {
	    System.out.println("error: expected " + expectedSum + ", but found " + actualSum);
	    return false;
	} else {
	    System.out.println("ok");
	}

	expectedSum = -6;
	actualSum = sum(2, -8);

	System.out.print("sum(2, -8): ");
	if (expectedSum != actualSum) {
	    System.out.println("error: expected " + expectedSum + ", but found " + actualSum);
	    return false;
	} else {
	    System.out.println("ok");
	}
	return true;
    }
	
    public static void main(String []args) {
	System.out.println("testing add(): ");
	if (addWorks()) {
	    System.out.println("add() ok");
	} else {
	    System.out.println("add() failed");
	}
    }
}