import java.util.Stack;

public class StackToQueue {

Stack<Integer> stack1 = new Stack<Integer>();
Stack<Integer> stack2 = new Stack<Integer>();

public void push(int node) {
stack1.push(node);
}

public int pop() {
if (stack1.isEmpty()&&stack2.isEmpty()) {
throw new RuntimeException("Queue is empty!");
}else {
if(stack2.empty()){
while(!stack1.empty()){
stack2.push(stack1.pop());
}
}
}

return stack2.pop();

}
}