MOD = 998244353

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

assert 1 <= N <= 2 * 10**5
assert all(s in (".", "U", "L", "R") for s in S)
assert len(S) == N

# dp[i][j] := i 本目の棒まで見て、最右の棒が方向 j に倒れている場合の数
# (j = 0: U,j = 1: L, j = 2: R)
dp = [[0] * 3 for _ in range(N + 1)]
dp[0][0] = 1

for i in range(N):
    if S[i] == ".":
        dp[i + 1][0] = (dp[i][0] + dp[i][1] + dp[i][2]) % MOD
        dp[i + 1][1] = (dp[i][0] + dp[i][1]) % MOD
        dp[i + 1][2] = (dp[i][0] + dp[i][1] + dp[i][2]) % MOD

    elif S[i] == "U":
        dp[i + 1][0] = (dp[i][0] + dp[i][1] + dp[i][2]) % MOD

    elif S[i] == "L":
        dp[i + 1][1] = (dp[i][0] + dp[i][1]) % MOD

    elif S[i] == "R":
        dp[i + 1][2] = (dp[i][0] + dp[i][1] + dp[i][2]) % MOD

print((dp[N][0] + dp[N][1] + dp[N][2]) % MOD)