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

MOD = 998244353
dp = [[0]*3 for _ in range(N)]
if S[0] == ".":
    for i in range(3):
        dp[0][i] = 1
elif S[0] == "L":
    dp[0][1] = 1
else:
    dp[0][2] = 1

def judge(A, B):
    return A == B or A == "."

for i in range(1, N):
    if judge(S[i], "U"):
        dp[i][0] += sum(dp[i-1])%MOD
        dp[i][0] %= MOD
    if judge(S[i], "L"):
        dp[i][1] += (dp[i-1][0]+dp[i-1][1])%MOD
        dp[i][1] %= MOD
    if judge(S[i], "R"):
        dp[i][2] += sum(dp[i-1])%MOD
        dp[i][2] %= MOD

print(sum(dp[-1])%MOD)