N = int(input())
S = input()
mod = 998244353

dp = [[0, 0, 0] for _ in range(N+1)]
dp[0][1] = 1
for i in range(N):
    if S[i] in 'L.':
        dp[i+1][0] += dp[i][0] + dp[i][1]
    if S[i] in 'U.':
        dp[i+1][1] += dp[i][0] + dp[i][1] + dp[i][2]
    if S[i] in 'R.':
        dp[i+1][2] += dp[i][0] + dp[i][1] + dp[i][2]
    
    for j in range(3):
        dp[i+1][j] %= mod

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