using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Text;
class Solution {

    
    static void Main(String[] args) 
        {
            DateTime d1 = DateTime.Now;
            try
            {
                string h1 = Console.ReadLine();
                h1 = Console.ReadLine();
                int i_start = Convert.ToInt32(h1.Split(' ')[0]);
                int j_start = Convert.ToInt32(h1.Split(' ')[1]);
                int i_end = Convert.ToInt32(h1.Split(' ')[2]);
                int j_end = Convert.ToInt32(h1.Split(' ')[3]);
                int idiff = i_end - i_start;
                int jdiff = j_end - j_start;

                string Output = "";
                string OneD = "R";
                string TwoDir = "L";
                List<string> Moves = new List<string>();
                if (idiff % 2 == 0)
                {
                    if (idiff < 0)
                    {
                        TwoDir = "U";
                        idiff *= -1;
                    }
                    while (idiff > 0)
                    {
                        if (jdiff < 0)
                        {
                            Moves.Add(TwoDir + "L");
                            jdiff += 1;
                        }
                        else
                        {
                            Moves.Add(TwoDir + "R");
                            jdiff -= 1;
                        }

                        idiff -= 2;
                    }
                    if (jdiff < 0)
                    {
                        OneD = "L";
                        jdiff *= -1;
                    }
                    while (jdiff > 0)
                    {
                        Moves.Add(OneD);
                        jdiff -= 2;
                    }
                    if (jdiff != 0) { }
                    string o = Moves.Count() + "\n" + String.Join(" ",Moves);
                    Console.WriteLine(o);
                    return ;

                }
                else
                {
                    Console.WriteLine("Impossible");
                    return ;
                }
            }
            catch (Exception exception)
            {
                return ;
            }

        }
}