What happens when we call the join() method 2 times within the current thread?

Given the following code, after calling the join() method first for t1 and then for t2, I was expecting the value of 'count' to be at least 20.000. But the output is a random number. How I see the execution: 1. t1.join(): main thread waits for t1 to finish, expected 'count' value: 10.000 2. t2.join(): main thread waits for t2 to finish, expected 'count' value: 20.000

public class Main {
private static int count = 0;
    public static void main(String[] args) {
        Thread t1 = new Thread(new Runnable() {
            @Override
            public void run() {
                for (int i = 0; i <= 10000 ; i++) {
                    count++;
                }
            }
        });

        Thread t2 = new Thread(new Runnable() {
            @Override
            public void run() {
                for (int i = 0; i <= 10000 ; i++) {
                    count++;
                }
            }
        });
        t1.start();
        t2.start();
        try {
            t1.join();
            t2.join();
        }catch (InterruptedException ie){

        }
        System.out.println(count);
    }
}