public class MakeChocolate {

    /********************************
     * We want make a package of goal kilos of chocolate. We have
     * small bars (1 kilo each) and big bars (5 kilos each).
     * Return the number of small bars to use, assuming we always
     * use big bars before small bars. Return -1 if it can't be done.
     *
     * See the verify lines below for examples of input
     * and expected output.
     *
     * Run this class, If you see errors, it is because the tests below
     * did not pass. Once the tests do pass, you will see a log of `Success!`
     ********************************/
    public static void main(String [] args) {
        try {
            // These are the tests that will run against your code
            // vars = small, big, goal, expected answer
            verify(4, 1, 9, 4);
            verify(4, 1, 10, -1);
            verify(4, 1, 7, 2);
            verify(6, 2, 7, 2);
            verify(4, 1, 5, 0);
            verify(4, 1, 4, 4);
            verify(5, 4, 9, 4);
            verify(9, 3, 18, 3);
            verify(3, 1, 9, -1);
            verify(1, 2, 7, -1);
            verify(1, 2, 6, 1);
            verify(1, 2, 5, 0);
            verify(6, 1, 10, 5);
            verify(6, 1, 11, 6);
            verify(6, 1, 12, -1);
            verify(6, 1, 13, -1);
            verify(6, 2, 10, 0);
            verify(6, 2, 11, 1);
            verify(6, 2, 12, 2);
            verify(60, 100, 550, 50);
            verify(1000, 1000000, 5000006, 6);
            verify(7, 1, 12, 7);
            verify(7, 1, 13, -1);
            verify(7, 2, 13, 3);
            System.out.println("Success!");
        } catch (Error err) {
            System.out.println(err.getMessage());
        }
    }

    /********************************
     * YOUR CODE BELOW HERE
     ********************************/
    private static int make(int small, int big, int goal) {
        int actualBig = big * 5;
        if (goal - actualBig < 0) {
            return make(small, big - 1, goal);
        }
        int leftover = goal - actualBig;
        if (leftover <= small) {
            return leftover;
        } else {
            return -1;
        }
    }

    /********************************
     * YOUR CODE ABOVE HERE
     ********************************/
    private static void verify(int small, int big, int goal, int expected) {
        int answer = make(small, big, goal);
        if (answer != expected) {
            throw new Error("wrong answer, expected " + answer + " to equal " + expected);
        }
    }
}