#include <bits/stdc++.h>
#include <atcoder/all>
using namespace std;
using namespace atcoder;
#define all(x) (x).begin(), (x).end()
#define rep(i, n) for (int i = 0; i < (int)(n); i++)
#define rrep(i, n) for(int i = (int)(n - 1); i >= 0; i--)
template <typename T> bool chmax(T &a,const T &b){if(a<b){a=b;return true;}return false;}
template <typename T> bool chmin(T &a,const T &b){if(a>b){a=b;return true;}return false;}
using ll = long long;
#define int ll
using vi = vector<int>;
using vvi = vector<vector<int>>;
using vb = vector<bool>;
using vvb = vector<vector<bool>>;
using vs = vector<string>;
using pii = pair<int, int>;
using mint = modint998244353;

signed main(){
  int n; string s; cin >> n >> s;
  vector<vector<mint>> dp(n + 1, vector<mint>(3, mint(0))); //0は直立、1は左、2は右
  dp.at(0).at(0) = 1;
  rep(i, n){
  	if(s.at(i) == 'U') dp.at(i + 1).at(0) = dp.at(i).at(0) + dp.at(i).at(1) + dp.at(i).at(2);
  	if(s.at(i) == 'L') dp.at(i + 1).at(1) = dp.at(i).at(0) + dp.at(i).at(1);
  	if(s.at(i) == 'R') dp.at(i + 1).at(2) = dp.at(i).at(0) + dp.at(i).at(1) + dp.at(i).at(2);
  	if(s.at(i) == '.'){
  		dp.at(i + 1).at(0) = dp.at(i).at(0) + dp.at(i).at(1) + dp.at(i).at(2);
  		dp.at(i + 1).at(1) = dp.at(i).at(0) + dp.at(i).at(1);
  		dp.at(i + 1).at(2) = dp.at(i).at(0) + dp.at(i).at(1) + dp.at(i).at(2);
  	}
  }
  mint ans = dp.at(n).at(0) + dp.at(n).at(1) + dp.at(n).at(2);
  rep(i, n + 1) rep(j, 3) cerr << dp.at(i).at(j).val() << (j == 2 ? '\n' : ' ');
  cout << ans.val() << endl;
}