import javax.xml.soap.Node;
import java.util.Stack;

public class Homework1 {

    public static void main(String[] args) {
        // Begin of arguments input sample
        if (args.length > 0) {
            String input = args[0];

            Stack inputstack = new Stack();

            Node root = null;
            for(int i=0;i<input.length();i++){
                char a = input.charAt(i);
                System.out.println(input.charAt(i));
                if(Character.isDigit(input.charAt(i))==true) {
                      inputstack.push(new Node(a + ""));
                }else {
                    int first,second,oparand;
                    Node parentNode = new Node(a + "");
                    parentNode.left = (Node) inputstack.pop();
                    parentNode.right = (Node) inputstack.pop();


                    inputstack.push(parentNode);

                    }
                }

                }
            }
            public static int calculate(Node n){

            }
            public static Node infix(Node n){

            }
            public static String inorder(Node n){

            }
            public class tree{
        public class Node{
            char key;
            Node left;
            Node right;
            Node parent;
        }
            }
        }

        // End of arguments input sample

        // TODO: Implement your project here