n = int(input())
s = input()

dp = [[0]*2 for _ in range(n+1)]
dp[0][0] = 1
mod = 998244353
for i in range(n):
    if s[i] == 'L' or s[i] == '.':
        dp[i+1][0] += dp[i][0]
    if s[i] == 'R' or s[i] == '.':
        dp[i+1][1] += sum(dp[i])
    if s[i] == 'U' or s[i] == '.':
        dp[i+1][0] += sum(dp[i])
    dp[i+1][0] %= mod
    dp[i+1][1] %= mod

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