#include<bits/stdc++.h>
using namespace std;
#define int long long
signed main() {
	int n;
	string s;
	cin >> n >> s;
	int mod = 998244353;
	vector<vector<int>> dp(n+1,vector<int>(3,0));
	dp[0][2]++;
	for(int i = 0; i < n; i++) {
		for(int j = 0; j < 3; j++) {
			char e = 'L';
			if(j == 1) e = 'R';
			else if(j == 2) e = 'U';
			if(s[i] != '.' && s[i] != e) continue;
			for(int k = 0; k < 3; k++) {
				if(k == 1 && j == 0) continue;
				dp[i+1][j]+=dp[i][k];
				dp[i+1][j]%=mod;
			}
		}
	}
	cout << (dp[n][0]+dp[n][1]+dp[n][2])%mod << endl;
}