using System;
using static System.Console;
using System.Linq;
using System.Collections.Generic;

class Program
{
    static int NN => int.Parse(ReadLine());
    static int[] NList => ReadLine().Split().Select(int.Parse).ToArray();
    static int[][] NArr(long n) => Enumerable.Repeat(0, (int)n).Select(_ => NList).ToArray();
    public static void Main()
    {
        Solve();
    }
    static void Solve()
    {
        var n = NN;
        var s = ReadLine();
        var mod = 998_244_353;
        var dp = new long[3];
        if (s[0] == 'L') dp[0] = 1;
        else if (s[0] == 'R') dp[1] = 1;
        else if (s[0] == 'U') dp[2] = 1;
        else
        {
            dp[0] = 1;
            dp[1] = 1;
            dp[2] = 1;
        }
        for (var i = 1; i < n; ++i)
        {
            var ndp = new long[3];
            if (s[i] == 'L')
            {
                ndp[0] = (dp[0] + dp[2]) % mod;
            }
            else if (s[i] == 'R')
            {
                ndp[1] = (dp[0] + dp[1] + dp[2]) % mod;
            }
            else if (s[i] == 'U')
            {
                ndp[2] = (dp[0] + dp[1] + dp[2]) % mod;
            }
            else
            {
                ndp[0] = (dp[0] + dp[2]) % mod;
                ndp[1] = (dp[0] + dp[1] + dp[2]) % mod;
                ndp[2] = (dp[0] + dp[1] + dp[2]) % mod;
            }
            dp = ndp;
        }
        WriteLine((dp[0] + dp[1] + dp[2]) % mod);
    }
}