# oj t -c "python3 main.py"
import sys,math
from collections import defaultdict,deque
from itertools import combinations,permutations,accumulate,product
from bisect import bisect_left,bisect_right
from heapq import heappop,heappush,heapify
#from more_itertools import distinct_permutations,distinct_combinations
#from sortedcontainers import SortedList,SortedSet
def input():return sys.stdin.readline().rstrip()
def ii(): return int(input())
def ms(): return map(int, input().split())
def li(): return list(map(int,input().split()))
inf = pow(10,18)
mod = 998244353
#/////////////////////////////////
N = ii()
S = input()
dp = [[0,0,0] for _ in range(N+1)]
if S[0]=="L" or S[0]==".": dp[1][0] = 1
if S[0]=="R" or S[0]==".": dp[1][1] = 1
if S[0]=="U" or S[0]==".": dp[1][2] = 1
for i in range(1,N):
    if S[i]=="L" or S[i]==".":
        dp[i+1][0] = dp[i][0] + dp[i][2]
        dp[i+1][0] %= mod
    if S[i]=="R" or S[i]==".":
        dp[i+1][1] = sum(dp[i])
        dp[i+1][1] %= mod
    if S[i]=="U" or S[i]==".":
        dp[i+1][2] = sum(dp[i])
        dp[i+1][2] %= mod
    
print(sum(dp[N])%mod)