from enum import IntEnum, auto


# ステート遷移
class E(IntEnum):
    S = 0       # S
    L = auto()  # L
    U = auto()  # U
    R = auto()  # R

    def nexts(self):
        match self:
            case E.S: return [E.L, E.U, E.R]
            case E.L: return [E.L, E.U, E.R]
            case E.U: return [E.L, E.U, E.R]
            case E.R: return [E.U, E.R]
        assert False

    @staticmethod
    def states():
        for fm in E:
            for to in fm.nexts():
                yield fm, to


def is_match(c: str, to) -> bool:
    match c:
        case '.': return True
        case 'L': return to == E.L
        case 'U': return to == E.U
        case 'R': return to == E.R
    assert False


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

dp = [[0] * len(E) for _ in range(N+1)]
dp[0][E.S] = 1
for i, c in enumerate(S):
    for fm, to in E.states():
        if dp[i][fm] == 0: continue
        if not is_match(c, to): continue
        dp[i+1][to] += dp[i][fm]
        dp[i+1][to] %= MOD

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