MOD = 998244353
N = int(input())
S = " " + input()

dp = [[0 for _ in range(3)] for _ in range(N+1)]
dp[0][2] = 1

for i in range(1, N+1):
    for j in range(3):
        if S[i] == "L" and j == 0:
            dp[i][0] = dp[i-1][0] + dp[i-1][2]
        if S[i] == "R" and j == 1:
            dp[i][1] = dp[i-1][0] + dp[i-1][1] + dp[i-1][2]
        if S[i] == "U" and j == 2:
            dp[i][2] = dp[i-1][0] + dp[i-1][1] + dp[i-1][2]
        if S[i] == ".":
            if j == 0: dp[i][0] = dp[i-1][0] + dp[i-1][2]
            if j == 1: dp[i][1] = dp[i-1][0] + dp[i-1][1] + dp[i-1][2]
            if j == 2: dp[i][2] = dp[i-1][0] + dp[i-1][1] + dp[i-1][2]
        dp[i][j] %= MOD

print(sum(dp[N]) % MOD)