#include <bits/stdc++.h>
//#include<atcoder/all>
using namespace std;
//using namespace atcoder;
using ll = long long;
//const ll mod = 1000000007;
const ll mod = 998244353;
int dx[4] = { 0,1,0,-1 }, dy[4] = { -1,0,1,0 };
ll n;
string s;
ll dp[3][200009];
int main() {
	cin >> n >> s;
	for (int i = 0; i <= n; i++) {
		for (int j = 0; j < 3; j++) {
			dp[j][i] = 0LL;
		}
	}
	for (int i = 1; i <= n; i++) {
		if (i == 1) {			
			if (s[i - 1] == 'U' || s[i - 1] == '.')dp[0][i]++;
			if (s[i - 1] == 'R' || s[i - 1] == '.')dp[1][i]++;
			if (s[i - 1] == 'L' || s[i - 1] == '.')dp[2][i]++;			
		}
		else {
			if (s[i - 1] == 'U' || s[i - 1] == '.')dp[0][i] = (dp[0][i] + dp[0][i - 1] + dp[1][i - 1] + dp[2][i - 1]) % mod;
			if (s[i - 1] == 'R' || s[i - 1] == '.')dp[1][i] = (dp[1][i] + dp[0][i - 1] + dp[1][i - 1] + dp[2][i - 1]) % mod;
			if (s[i - 1] == 'L' || s[i - 1] == '.')dp[2][i] = (dp[2][i] + dp[0][i - 1] + dp[2][i - 1]) % mod;
		}
	}
	ll ans = (dp[0][n] + dp[1][n] + dp[2][n]) % mod;
	cout << ans << endl;
}