#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
const int mod = 998244353;
#define REP(i, x, y) for (auto i = (x); i < (y); i++)
#define RREP(i, x, y) for (auto i = (y) - 1; (x) <= i; i--)
#define ALL(x) (x).begin(), (x).end()
#pragma GCC optimize("O3")
int main(){
  ios::sync_with_stdio(false);
  cin.tie(nullptr);
  int N;
  string S;
  cin >> N >> S;
  vector<array<ll,3>> dp(N);
  if(S[0] == 'L' || S[0] == '.')dp[0][0] += 1;
  if(S[0] == 'R' || S[0] == '.')dp[0][1] += 1;
  if(S[0] == 'U' || S[0] == '.')dp[0][2] += 1;
  REP(i, 1, N){
    if(S[i] == 'L' || S[i] == '.'){
      dp[i][0] += dp[i-1][0] + dp[i-1][2];
    }
    if(S[i] == 'R' || S[i] == '.'){
      dp[i][1] += dp[i-1][0] + dp[i-1][1] + dp[i-1][2];
    }
    if(S[i] == 'U' || S[i] == '.'){
      dp[i][2] += dp[i-1][0] + dp[i-1][1] + dp[i-1][2];
    }
    dp[i][0] %= mod;
    dp[i][1] %= mod;
    dp[i][2] %= mod;
  }
  ll ans = 0;
  ans += dp[N-1][0];
  ans += dp[N-1][1];
  ans += dp[N-1][2];
  ans %= mod;
  cout << ans << "\n";
  return 0;
}
/*
  File : ~/yukicoder/midoriika_3rd/H.cpp
  Date : 2024/10/12
  Time : 15:08:33
*/