@Override
    public String toString() {
        if (min == max) {
            return String.valueOf(min);
        } else if (max == Short.MAX_VALUE) {
            return String.valueOf(min) + "+";
        } else {
            return String.valueOf(min) + "-" + String.valueOf(max);
        }
    }
@Test
    public void testToString() {
        assertEquals("1-2", v(1, 2).toString());
        assertEquals("1", v(1, 1).toString());
        assertEquals("1+", v(1, Short.MAX_VALUE).toString());
        assertEquals("100-200", v(100, 200).toString());
    }