Object Reference Variable Aliasing

Consider the following code segment.

ArrayList<String> list1 = new ArrayList<String>();
ArrayList<String> list2 = new ArrayList<String>();
ArrayList<String> list3 = list1;

list1.add("Java");
list2.add("Python");
list3.add("C++");

After the code segment is executed, what is the size of the ArrayList object referenced by list1?