N = int(input())
S = list(input())
mod = 998244353
pre = [1, 0, 0]
for i in range(N):
    dp = [0, 0, 0]
    if S[i] == "L" or S[i] == ".":
        dp[0] += (pre[0] + pre[2]) % mod
    if S[i] == "R" or S[i] == ".":
        dp[1] += sum(pre) % mod
    if S[i] == "U" or S[i] == ".":
        dp[2] += sum(pre) % mod
    pre, dp = dp, pre
    
print(sum(pre) % mod)