Java unisex bathroom

I have to solve this problem using Java semaphores, but I have no idea how, and I cannot find any related Java materials. This is how it goes:

There are to kinds of threads: men and women. Both wants to use same resources which quantity is BATHROOM_SIZE. 5 rules:

1. Every thread, after signaling need of using resource, should wait until he will be able to use it.
2. Prevent situation, when more than BATHOOM_SIZE threads is using resource concurrently.
3. Prevent woman and man use bathoom in the same time.
4. Threads should use resources concurrently. If there are many threads of one type, up to BATHROOM_SIZE threads should use resource.
5. Prevent starvation.

Results

Works for:

1woman, 1man, 5women, 5men

Fails for:

5women1men, 5men1women, 2men2women, 5men5women.

I've been trying to make it work since Monday and now I've run out of ideas.

Code

So my task is to write Bathroom.java class which implements BathroomInterface:

public interface BathroomInterface {

    public static final int BATHROOM_SIZE = 3; //3 is just example
    void manEnter();
    void manExit();
    void womanEnter();
    void womanExit();
}

In system there are a number of man and woman threads which work like this:

for(int i = 0; i < n; i++) {
  bathroom.manEnter();
  //uses bathroom random amount of time
  bathroom.manExit();
}

for(int i = 0; i < m; i++) {
  bathroom.womanEnter();
  //uses bathroom random amount of time
  bathroom.womanExit();
}

I also have scheme of Bathroom.java class, I have to extend:

import java.util.concurrent.Semaphore;

public class Bathroom implements BathroomInterface {

    
    private Semaphore mutex = new Semaphore(1, true);

    public void womanEnter() {
        mutex.acquireUninterruptibly();
    }

    public void womanExit() {