import java.util.Stack;

public class Queue_byTwoStacks {

public static class Queue_stack{

static Stack<Integer> s1 = new Stack<>();

static Stack<Integer> s2 = new Stack<>();

public static boolean isEmpty(){

return s1.isEmpty();

}

public static void add(int data){

while(!s1.isEmpty()){

s2.push(s1.pop());

}

s1.push(data);

while(!s2.isEmpty()){

s1.push(s2.pop());

}

}

public static int remove(){

if(isEmpty()){

System.out.println("empty queue");

return -1;

}

return s1.pop();

}

public static int peek(){

if(isEmpty()){

System.out.println("empty queue");

return -1;

}

return s1.peek();

}

}

public static void main(String[] args) {

Queue_stack q = new Queue_stack();

q.add(1);

q.add(2);

q.add(3);

q.add(4);

while(!q.isEmpty()){

System.out.println(q.peek());

q.remove();

}

}

}