MOD = 998244353
n = int(input())
s = input()

dp = [0, 0, 0]
if s[0] == "L": dp[0] += 1
if s[0] == "R": dp[1] += 1
if s[0] == "U": dp[2] += 1
if s[0] == ".": dp = [1, 1, 1]

for i in range(1, n):
    ndp = [0, 0, 0]
    if s[i] == "L" or s[i] == ".":
        ndp[0] = (dp[0] + dp[2]) % MOD
    if s[i] == "R" or s[i] == ".":
        ndp[1] = sum(dp) % MOD
    if s[i] == "U" or s[i] == ".":
        ndp[2] = sum(dp) % MOD

    dp = ndp[::]
print(sum(dp)%MOD)