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();
        }
    }
}