using System;
using System.IO;

namespace ConsoleApp6
{
    class Stack
    {
        int[] Buf;
        int n;
        int top;
        bool empty, full;
        public int nSt { get { return n; } }
        public bool Empty { get { return empty; } private set { empty = value; } }
        public bool Full { get { return full; } private set { full = value; } }
        public Stack(int n)
        {
            if (n == 0) throw new Exception("01");
            this.n = n;
            Buf = new int[n];
            top = 0;
            Empty = true;
            Full = false;
        }
        public void push(int t)
        {
            if (Full) throw new Exception("21");
            Buf[top++] = t;
            if (top >= n) Full = true;
            Empty = false;
        }
        public int pop()
        {
            if (Empty) throw new Exception("11");
            if (top == 0) Empty = true;
            return Buf[--top];
        }
        class Program
        {
            static void Main()
            {
                int i;
                Stack oSt;
                int r;
                StreamReader R = new StreamReader("in.txt");
                StreamWriter W = new StreamWriter("out.txt");
                int[] A;
                string[] As;
                int n;
                As = R.ReadLine().Split(',');
                n = As.Length;
                A = new int[n];
                for (i = 0; i < n; i++) A[i] = Convert.ToInt32(As[i]);
                for (i = 0; i <= 4; i++)
                {
                    try
                    {
                        switch (i)
                        {
                            case 0: oSt = new Stack(i); break;
                            case 1: oSt = new Stack(1); r = oSt.pop(); break;
                            case 2:
                                oSt = new Stack(1);
                                oSt.push(i); oSt.push(i + 1); break;
                            case 3:
                                oSt = new Stack(3);
                                {
                                    for (int j = 0; j < oSt.nSt; j++)
                                    {
                                        oSt.push(j + 1);
                                    }
                                    W.WriteLine("Stack 3: O'key");
                                    for (int j = 0; j < oSt.nSt; j++)
                                    {
                                        W.Write(" " + oSt.pop());
                                    }
                                    W.WriteLine();
                                }
                                break;
                            case 4:
                                oSt = new Stack(n);
                                {
                                    for (int j = 0; j < oSt.nSt; j++)
                                        oSt.push(A[j]);
                                    W.WriteLine("Stack 4: O'key");
                                    while (!oSt.Empty)
                                        W.Write(" " + oSt.pop());
                                    W.WriteLine();
                                }
                                break;
                        }
                    }
                    catch (Exception ob)
                    {
                        switch (ob.Message[0])
                        {
                            case '0':
                                W.WriteLine("size=0"); break;
                            case '1':
                                W.WriteLine("read error"); break;
                            case '2':
                                W.WriteLine("write error"); break;
                        }
                    }
                }
                R.Close();
                W.Close();
            }
        }
    }
}