import sys


def input():
    return sys.stdin.readline().strip()


def main():
    MOD = 998244353

    n = int(input())
    a = input()

    if a[0] == ".":
        dp = [1, 1, 1]
    elif a[0] == "L":
        dp = [1, 0, 0]
    elif a[0] == "U":
        dp = [0, 1, 0]
    elif a[0] == "R":
        dp = [0, 0, 1]

    for i in range(1, n):
        dp = [dp[0] + dp[1], dp[0] + dp[1] + dp[2], dp[0] + dp[1] + dp[2]]
        if a[i] == "L":
            dp[1] = dp[2] = 0
        if a[i] == "U":
            dp[0] = dp[2] = 0
        if a[i] == "R":
            dp[0] = dp[1] = 0
        dp = [x % MOD for x in dp]

    print(sum(dp) % MOD)


if __name__ == "__main__":
    main()