#include <bits/stdc++.h>
#include <atcoder/all>
using mint = atcoder::modint998244353;
using namespace std;
int main(){
	int N;
	cin >> N;
	string  S;
	cin >> S;
	vector<vector<mint>> dp(N + 1, vector<mint>(3));
	dp[0][1] = 1;
	for (int i = 0; i < N; i++){
		if (S[i] == 'L' or S[i] == '.'){
			dp[i + 1][0] = dp[i][0] + dp[i][1];
		}
		if (S[i] == 'U' or S[i] == '.'){
			dp[i + 1][1] = dp[i][0] + dp[i][1] + dp[i][2];
		}
		if (S[i] == 'R' or S[i] == '.'){
			dp[i + 1][2] = dp[i][0] + dp[i][1] + dp[i][2];
		}
	}
	cout << accumulate(dp[N].begin(), dp[N].end(), mint(0)).val() << endl;
}