import java.util.Stack;

/* This file uses the Keyboard class from 101. */

/**
 * A very small calculator that will handle any expression using the 4 standard
 * operators.
 * 
 * @author Robert Sheehan
 * @version 14/09/2006
 */
public class RPNCalculator {

	public static void main(String[] args) {
		Stack<Double> values = new Stack<Double>();
		String input;
		while ((input = Keyboard.readInput()).length() > 0) {
			try {
				double number = Double.parseDouble(input);
				values.push(number);
				System.out.println(values);
			} catch (NumberFormatException e) {
				if (values.size() < 2) {
					System.out.println("Not enough numbers on the stack.");
					System.out.println(values);
					continue;
				}
				double x, y;
				double answer;
				char operator;
				if (input.length() > 1)
					operator = 'z'; // an incorrect operator
				else
					operator = input.charAt(0);
				switch (operator) {
				case '+':
					y = values.pop();
					x = values.pop();
					answer = x + y;
					break;
				case '-':
					y = values.pop();
					x = values.pop();
					answer = x - y;
					break;
				case '*':
					y = values.pop();
					x = values.pop();
					answer = x * y;
					break;
				case '/':
					y = values.pop();
					x = values.pop();
					answer = x / y;
					break;
				default:
					System.out.println("Incorrect operator.");
					System.out.println(values);
					continue;
				}
				values.push(answer);
				System.out.println(values);
			}
		}
	}

}