What does the following Java code output?

import java.util.PriorityQueue;
import java.util.Queue;
public class Main {
    public static void main(String[] args) {
        Queue<Integer> numbers = new PriorityQueue<>();
        numbers.add(3);
        numbers.add(1);
        numbers.add(2);
        System.out.println(numbers.poll());
    }
}