import java.util.ArrayList;
import java.util.List;
public class MyStack {
private final List numbers = new ArrayList<>(1000);
public void push(int x) {
numbers.add(x);
}
public int pop() {
int element = numbers.get(numbers.size() - 1);
numbers.remove(numbers.size() - 1);
return element;
}
public int top() {
return numbers.get(numbers.size() - 1);
}
/** Returns whether the stack is empty. */
public boolean empty() {
return numbers.isEmpty();
}
}