from collections import deque, defaultdict, Counter
from bisect import bisect_left, bisect_right
from itertools import permutations, combinations
from functools import cmp_to_key, cache
from heapq import heappop, heappush
import math, sys
import pypyjit
pypyjit.set_param('max_unroll_recursion=-1')
sys.setrecursionlimit(10**7)
_int = lambda x: int(x)-1
MOD = 998244353
INF = 1<<62
Yes, No = "Yes", "No"

N = int(input())
S = input()

dp = [[0]*3 for _ in range(N+1)]
dp[0][0] = 1
for i in range(N):
    if S[i] == "L" or S[i] == ".":
        dp[i+1][1] = dp[i][0]+dp[i][1]
        dp[i+1][1] %= MOD
    if S[i] == "R" or S[i] == ".":
        dp[i+1][2] = dp[i][0]+dp[i][1]+dp[i][2]
        dp[i+1][2] %= MOD
    if S[i] == "U" or S[i] == ".":
        dp[i+1][0] = dp[i][0]+dp[i][1]+dp[i][2]
        dp[i+1][0] %= MOD
print(sum(dp[N])%MOD)