#1114 Print in Order.java

//https://leetcode.com/problems/print-in-order/
import java.util.concurrent.*;
class Foo {
    Semaphore s1,s2;
    public Foo() {
        s1 = new Semaphore(0);
        s2 = new Semaphore(0);
    }

    public void first(Runnable printFirst) throws InterruptedException {
        printFirst.run();
        s1.release();
    }

    public void second(Runnable printSecond) throws InterruptedException {
        s1.acquire();
        printSecond.run();
        s2.release();
    }

    public void third(Runnable printThird) throws InterruptedException {
        s2.acquire();
        printThird.run();
    }
}