SumNumber.java

import java.util.Scanner;
import java.util.List;
import java.util.ArrayList;


public class SumNumber {
    public static void main(String [] args) {
        Scanner sc = new Scanner(System.in);
        List<Integer> values = new ArrayList<Integer>();

        while(true) {
            String line = sc.nextLine();
            if ("q".equals(line)) {
                break;
            }

            String [] parts = line.split(" ");
            switch(parts[0]) {
                case "p":
                    for (int i : values) {
                        System.out.println(i);
                    }
                    break;

                case "s":
                    int sum = 0;
                    for (int i : values) {
                        sum += i;
                    }
                    System.out.println(sum);
                    values.clear();
                    values.add(sum);
                    break;

                case "a":
                    int num = Integer.valueOf(parts[1]);
                    values.add(num);
                    break;

                case "d":
                    int last = values.size() - 1;
                    values.remove(last);
                    break;

                default:
                    System.out.println("Unsupported : " + line);
                    break;
            }
        }
    }
}