#include <bits/stdc++.h>
using namespace std;
#ifdef LOCAL
  #include "settings/debug.cpp"
#else
  #define Debug(...) void(0)
#endif
#define rep(i, n) for (int i = 0; i < (n); ++i)
using ll = long long;
using ull = unsigned long long;

#include <atcoder/modint>
using mint = atcoder::modint998244353;

int main() {
  int n;
  string s;
  cin >> n >> s;
  vector dp(n, vector<mint>(3));
  rep(i, n) {
    char c = s[i];
    if (c == 'L' || c == '.') {
      if (i == 0) {
        dp[i][0] = 1;
      }
      else {
        dp[i][0] = dp[i - 1][0] + dp[i - 1][2];
      }
    }
    if (c == 'R' || c == '.') {
      if (i == 0) {
        dp[i][1] = 1;
      }
      else {
        dp[i][1] = dp[i - 1][0] + dp[i - 1][1] + dp[i - 1][2];
      }
    }
    if (c == 'U' || c == '.') {
      if (i == 0) {
        dp[i][2] = 1;
      }
      else {
        dp[i][2] = dp[i - 1][0] + dp[i - 1][1] + dp[i - 1][2];
      }
    }
  }
  cout << (dp[n - 1][0] + dp[n - 1][1] + dp[n - 1][2]).val() << endl;
  return 0;
}