Hi, I wrote
package com.codegym.task.task01.task0137;

Only 20 will do


public class Solution {
    public static int a = 1;
    public static int b = 3;
    public static int c = 9;
    public static int d = 27;

    public static void main(String[] args) {

        int result = + a - b + c - d;

To this I tried to use Math.abs() to get a positive number from negative number, but verification's last line keeps writing "incorrectly places signs". I also tried to add a variable to add it and get positive number. The same mistake. What's wrong?