#include<bits/stdc++.h>
#include<atcoder/all>
using namespace std; 
using namespace atcoder;
using mint = modint998244353;
#define rep(i, n) for (int i = 0; i < (int)(n); i++)
#define length size()
#define __STDCPP_FLOAT128_T__
#define Real1024 float128_t
#define int long long
#define ll long long
#define ALL(v) (v).begin(), (v).end()
constexpr ll inf = 1001001001001001001ll;
constexpr ll mod = /* 1000000007*/ 998244353;
constexpr double pi = 3.141592653589793;

//小数出力
//cout << setprecision(12);
//max
template< typename T1, typename T2 >
inline bool chmax(T1 &a, T2 b) { return a < b && (a = b, true); }
//min
template< typename T1, typename T2 >
inline bool chmin(T1 &a, T2 b) { return a > b && (a = b, true); }
//print
void print() { cout << '\n'; }
template<typename T>
void print(const T &t) { cout << t << '\n'; }
template<typename Head, typename... Tail>
void print(const Head &head, const Tail &... tail) {
    cout << head << ' ';
    print(tail...);
}
//join
template<typename T> string join(vector<T> &vec ,const string &sp){
    int si = vec.length;
    if(si==0){
        return "";
    }else{
        stringstream ss;
        rep(i,si-1){
            ss << vec[i] << sp;
        }
        ss << vec[si - 1];
        return ss.str();
    }
}
bool in_range(int l,int x,int r){//閉区間
  return (l <= x ) && (x <= r);
}
int div_ceil(int x,int y){
  return (x+y-1)/y;
}
int blood(char x,char y){
  if(x == 'O' && y == 'O') return 3;
  if((x == 'A' && y == 'B') || (x == 'B' && y == 'A')) return 2;
  if(x == 'A' || y == 'A') return 0;
  return 1;
}
//Template End
signed main(void){
  int n;
  cin >> n;
  string s;
  cin >> s;
  vector<vector<mint>> dp(3,vector<mint>(n+1,0));//lru
  dp[2][0] = 1;
  rep(i,n){
    switch(s[i]){
      case 'L':
      dp[0][i+1] += dp[0][i] + dp[2][i];
      break;
      case 'R':
      dp[1][i+1] += dp[0][i]+dp[1][i]+dp[2][i];
      break;
      case 'U':
      dp[2][i+1] += dp[0][i]+dp[1][i]+dp[2][i];
      break;
      default:
      dp[0][i+1] += dp[0][i] + dp[2][i];
      dp[1][i+1] += dp[0][i]+dp[1][i]+dp[2][i];
      dp[2][i+1] += dp[0][i]+dp[1][i]+dp[2][i];
    }
    //rep(j,3) cout << dp[j][i+1].val() << " ";
    //cout << endl;
  }
  mint ans = 0;
  rep(i,3) ans += dp[i][n];
  cout << ans.val() << endl;
}