from enum import IntEnum, auto
from functools import cache


class E(IntEnum):
    S = 0       # 開始
    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
    @cache
    def states():
        res = []
        for fm in E:
            for to in fm.nexts():
                res.append((fm, to))

        return res


def state_dp(xs: list, op, e, init: dict):
    dp = [e for _ in range(len(E))]
    for k, v in init.items():
        dp[k] = v

    for x in xs:
        pp = [e for _ in range(len(E))]
        dp, pp = pp, dp
        for fm, to in E.states():
            if not is_valid(to, pp[fm], x): continue
            dp[to] = op(to, dp[to], fm, pp[fm], x)

    return dp


def is_valid(to: E, fm_v, v) -> bool:
    match v:
        case '.': return True
        case 'L': return to == E.L
        case 'U': return to == E.U
        case 'R': return to == E.R
    assert False


def op(to: E, to_v, fm: E, fm_v, v):
    return (to_v + fm_v) % MOD


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

dp = state_dp(S, op, 0, {E.S: 1})
ans = sum(dp) % MOD
print(ans)