using System;
using System.Collections.Generic;
using System.Linq;

// https://yukicoder.me/problems/no/2926
class Program
{
    static string InputPattern = "InputX";

    static List<string> GetInputList()
    {
        var WillReturn = new List<string>();

        if (InputPattern == "Input1") {
            WillReturn.Add("3");
            WillReturn.Add("..L");
        }
        else if (InputPattern == "Input2") {
            WillReturn.Add("6");
            WillReturn.Add("..L..R");
        }
        else if (InputPattern == "Input3") {
            WillReturn.Add("8");
            WillReturn.Add(".RL..U..");
        }
        else if (InputPattern == "Input4") {
            WillReturn.Add("30");
            WillReturn.Add(".....R.....U...R..L.........L.");
        }
        else {
            string wkStr;
            while ((wkStr = Console.ReadLine()) != null) WillReturn.Add(wkStr);
        }
        return WillReturn;
    }

    const long Hou = 998244353;

    static void Main()
    {
        List<string> InputList = GetInputList();
        char[] CharArr = InputList[1].ToCharArray();

        // 場合の数[Lが使用不可か?]
        // 0 Lが使用可
        // 1 Lが使用不可
        long[] PrevDP = new long[2];
        PrevDP[0] = 1;

        foreach (char EachChar in CharArr) {
            long[] CurrDP = new long[2];

            for (long I = 0; I <= 1; I++) {
                if (PrevDP[I] == 0) continue;

                Action<char> SendAct = (pNewChar) =>
                {
                    if (pNewChar == 'L' && I == 1) return;

                    if (pNewChar == 'R') {
                        CurrDP[1] += PrevDP[I];
                        CurrDP[1] %= Hou;
                    }
                    else {
                        CurrDP[0] += PrevDP[I];
                        CurrDP[0] %= Hou;
                    }
                };

                if (EachChar == 'L') {
                    SendAct('L');
                }
                if (EachChar == 'R') {
                    SendAct('R');
                }
                if (EachChar == 'U') {
                    SendAct('U');
                }
                if (EachChar == '.') {
                    SendAct('L');
                    SendAct('R');
                    SendAct('U');
                }
            }
            PrevDP = CurrDP;
        }

        long Answer = 0;
        foreach (long EachLong in PrevDP) {
            Answer += EachLong;
            Answer %= Hou;
        }
        Console.WriteLine(Answer);
    }
}