// holding/Ex15.java
// TIJ4 Chapter Holding, Exercise 15, page 415
/* Stacks are often used to evaluate expressions in programming 
* languages. Using net.mindview.util.Stack, evaluate the following
* expression, where '+' means "push the following letter onto the 
* stack," and '-' means "pop the top of the stack and print it":
* "+U+n+c---+e+r+t---+a+i+n+t+y---+ -+r+u--+l+e+s---"
*/
import net.mindview.util.*;

public class Ex15 {
	public static void main(String[] args) {
		Stack<Character> sc = new Stack<Character>();
		sc.push('U');
		sc.push('n');
		sc.push('c');
		System.out.print(sc.pop());
		System.out.print(sc.pop());
		System.out.print(sc.pop());
		sc.push('e');
		sc.push('r');
		sc.push('t');
		System.out.print(sc.pop());
		System.out.print(sc.pop());
		System.out.print(sc.pop());
		sc.push('a');
		sc.push('i');
		sc.push('n');
		sc.push('t');
		System.out.print(sc.pop());
		System.out.print(sc.pop());
		System.out.print(sc.pop());
		sc.push(' ');
		System.out.print(sc.pop());
		sc.push('r');
		sc.push('u');
		System.out.print(sc.pop());
		System.out.print(sc.pop());
		sc.push('l');
		sc.push('e');
		sc.push('s');
		System.out.print(sc.pop());
		System.out.print(sc.pop());
		System.out.print(sc.pop());		
	}		
}