#include <iostream>
#include <vector>
using Int = long long;
constexpr int MO = 998244353;
int main() {
	int N;
	std::cin >> N;
	std::string S;
	std::cin >> S;
	Int dp[N][3]{};
	if (S[0] == 'L' || S[0] == '.') dp[0][0] = 1;
	if (S[0] == 'R' || S[0] == '.') dp[0][1] = 1;
	if (S[0] == 'U' || S[0] == '.') dp[0][2] = 1;
	for (int i = 1; i < N; ++i) {
		if (S[i] == 'L' || S[i] == '.') {
			dp[i][0] += dp[i - 1][0] + dp[i - 1][2];
			dp[i][0] %= MO;
		}
		if (S[i] == 'R' || S[i] == '.') {
			dp[i][1] += dp[i - 1][0] + dp[i - 1][1] + dp[i - 1][2];
			dp[i][1] %= MO;
		}
		if (S[i] == 'U' || S[i] == '.') {
			dp[i][2] += dp[i - 1][0] + dp[i - 1][1] + dp[i - 1][2];
			dp[i][2] %= MO;
		}
	}
	std::cout << (dp[N - 1][0] + dp[N - 1][1] + dp[N - 1][2]) % MO << std::endl;
}