class Stack {
    private int[] array;
    private int stackTop;

    Object lock;

    Stack(int capacity) {
        array = new int[capacity];
        stackTop = -1;
        lock = new Object();
    }

    public synchronized boolean push(int element) {
        if (isFull())
            return false;
        ++stackTop;

        try {
            Thread.sleep(1000);
        } catch (Exception e) {}
            array[stackTop] = element;
            return true;
        
    }

    public synchronized int pop() {
        if (isEmpty())
            return Integer.MIN_VALUE;
        int obj = array[stackTop];
        array[stackTop] = Integer.MIN_VALUE;
        try {
            Thread.sleep(1000);
        } catch (Exception e) { }
            stackTop--;
            return obj;
        

    }

    public boolean isEmpty() {
        return stackTop < 0;
    }

    public boolean isFull() {
        return stackTop >= array.length - 1;
    }
}

public class ThreadStack {
    public static void main(String[] args) {
        System.out.println("Main is starting");

        Stack st = new Stack(5);
        new Thread(()->{
            int counter =0;
            while(++counter<5){
                System.out.println("pushed: "+st.push(100));
            }
        },"pusher").start();

        new Thread(()->{
            int counter =0;
            while(++counter<5){
                System.out.println("pushed: "+st.pop());
            }
        },"popper").start();
        System.out.println("Main is ending!");

    }

}