def main():
    N = int(input())
    S = input()
    MOD = 998244353
    dp_table = [[0, 0] for _ in range(N+1)]
    # 0: R 1: R以外
    dp_table[0][1] = 1

    for idx, letter in enumerate(S):
        match letter:
            case "L":
                dp_table[idx+1][1] = dp_table[idx][1]
            case "R":
                dp_table[idx+1][0] = dp_table[idx][0] + dp_table[idx][1]
            case "U":
                dp_table[idx+1][1] = dp_table[idx][0] + dp_table[idx][1]
            case ".":
                dp_table[idx+1][0] = dp_table[idx][0] + dp_table[idx][1]
                dp_table[idx+1][1] = dp_table[idx][0] + dp_table[idx][1] * 2
            case _:
                raise ValueError
        dp_table[idx+1][1] %= MOD
        dp_table[idx+1][0] %= MOD

    print((dp_table[-1][0] + dp_table[-1][1]) % MOD)


if __name__ == "__main__":
    main()