import java.util.Stack;
public class Solution {
  Stack<Integer> stack1 = new Stack<Integer>();
  Stack<Integer> stack2 = new Stack<Integer>();
  public void push(int node) {
    stack1.push(node);
  }
  public int pop() {
    while(!stack1.isEmpty()){
      stack2.push(stack1.pop());
    }
    int pop = stack2.pop();
    while(!stack2.isEmpty()){
      stack1.push(stack2.pop());
    }
    return pop;
  }
}