What is output by the code below?
List<String> bigList = new ArrayList<String>();
bigList.add(0,"one");
bigList.add("two");
bigList.add(0,"three");
bigList.add("four");
bigList.remove(0);
bigList.add(0,"five");
bigList.set(2,"six");
bigList.set(3,"seven");
bigList.add("zero");
System.out.println(bigList.indexOf("six"));