from collections import *
from itertools import *
from functools import cache, partial
from pprint import pprint
import sys
from typing import Any, Final

try:
    from icecream import ic
except ImportError:  # Graceful fallback if IceCream isn't installed.
    ic = lambda *a: None if not a else (a[0] if len(a) == 1 else a)  # noqa
debug = partial(print, file=sys.stderr)
dpprint = partial(pprint, stream=sys.stderr)
sys.setrecursionlimit(10**6)
MOD = 998244353

N = int(input())
S = ["Z"] + list(input())
N += 1

# dp([i])[j] := i文字目まで見たときに、j番目の棒が L: 0 (左に) R: 1 (右に) U: 2 (倒れていない) 状態である場合の数
INF = float("inf")
dp = [0] * 3
dp[2] = 1
# ic(dp)

for i in range(1, N):
    dp2 = [0] * 3
    s = S[i]
    # ic(s)
    sum_ = sum(dp) % MOD
    if s == "L":
        j = 0
        dp2[j] += sum_ - dp[1]
    elif s == "R":
        j = 1
        dp2[j] += sum_
    elif s == "U":
        j = 2
        dp2[j] += sum_
    elif s == ".":
        j = 0
        dp2[j] += sum_ - dp[1]
        j = 1
        dp2[j] += sum_
        j = 2
        dp2[j] += sum_

    dp = [d % MOD for d in dp2]
    # ic(dp)

ans = sum(dp) % MOD
print(ans)