using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace ConsoleApplication33
{
    class Program
    {
        static void Main(string[] args)
        {
            StringTool objString = new StringTool();

            Console.WriteLine(objString.LettersClean(Console.ReadLine()));
            Console.WriteLine(objString.DigitsClean(Console.ReadLine()));
            Console.WriteLine(objString.GetLastProcessedString());
            objString.CleanHistory();
            Console.WriteLine(objString.GetLastProcessedString());
        }
    }

    class StringTool
    {
        private List<string> StringList = new List<string>();

        public string LettersClean(string somestring)
        {
            StringList.Add(somestring);
            string resultString = null;
            foreach (char a in somestring)
                if (!char.IsLetter(a))
                    resultString += a;
            return resultString;
        }

        public string DigitsClean(string somestring)
        {
            StringList.Add(somestring);
            string resultString = null;
            foreach (char a in somestring)
                if (!char.IsDigit(a))
                    resultString += a;
            return resultString;
        }

        public string GetLastProcessedString()
        {
            string previous;
            if (StringList != null)
                previous = StringList[StringList.Count - 1];
            else
                previous = null;
            return  previous;
        }

        public void CleanHistory()
        {
           StringList.Clear();
        }
    }
}