import sys
mod = 998244353
mod2 = 10**9+7

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