n = int(input())
S = list(input())
mod = 998244353
# dp[i][j] := i番目の棒までの倒し方を決めて、i番目の状態がjであるときの通り数
# 0=>U, 1=>L, 2=>R
dp = [[0 for j in range(3)] for i in range(n+1)]
dp[0][0] = 1


for i in range(n):
    for j in range(3):
        
        # 倒す方向が決まっている場合
        if(S[i] == "U"):
            dp[i+1][0] += dp[i][j]
            dp[i+1][0] %= mod
            
        elif(S[i] == "L"):
            # R→Lの遷移禁止
            if(j == 2):
                continue
            dp[i+1][1] += dp[i][j]
            dp[i+1][1] %= mod
        elif(S[i] == "R"):
            dp[i+1][2] += dp[i][j]
            dp[i+1][2] %= mod
        
        # 自由に倒してよい場合
        elif(S[i] == "."):
            for k in range(3):
                # R→Lの遷移禁止
                if(j==2 and k==1):
                    continue
                dp[i+1][k] += dp[i][j]
                dp[i+1][k] %= mod
    
print(sum(dp[-1]) % mod)