N = int(input())
S = input()
dp = [[0,0] for _ in range(N+1)]
dp[0][0] = 1
mod = 998244353
for i in range(N):
    if S[i] == 'L':
        dp[i+1][0] = dp[i][0]
    elif S[i] == 'R':
        dp[i+1][1] = dp[i][0]+dp[i][1]
    elif S[i] == 'U':
        dp[i+1][0] = dp[i][0]+dp[i][1]
    else:
        dp[i+1][0] = dp[i][0]*2+dp[i][1]
        dp[i+1][1] = dp[i][0]+dp[i][1]
    dp[i+1][0] %= mod
    dp[i+1][1] %= mod
print(sum(dp[-1])%mod)