#include <bits/stdc++.h>
using namespace std;
#define rep(i, n) for (int i = 0; i < (int)(n); i++)
typedef vector<int> VI;
typedef vector<VI> VVI;
typedef vector<long long> VL;
typedef vector<VL> VVL;
typedef long long LL;
#define all(a) (a).begin(), (a).end()
#define Yes(n) cout << ((n) ? "Yes" : "No"  ) << endl
#define ALL(a)  (a).begin(),(a).end()
#define pb push_back

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

int main() {
    int n;cin>>n;
    string s;cin>>s;
    mint L[n]={},R[n]={},U[n]={};
    if(s[0]=='L'){L[0]=1;}
    else if(s[0]=='R'){R[0]=1;}
    else if(s[0]=='U'){U[0]=1;}
    else{L[0]=1;R[0]=1;U[0]=1;}
    rep(i,n-1){
      if(s[i+1]=='L'){
        L[i+1]=L[i]+U[i];
      }
      else if(s[i+1]=='R'){
        R[i+1]=L[i]+R[i]+U[i];
      }
      else if(s[i+1]=='U'){
        U[i+1]=L[i]+R[i]+U[i];
      }
      else{
        L[i+1]=L[i]+U[i];
        R[i+1]=L[i]+R[i]+U[i];
        U[i+1]=L[i]+R[i]+U[i];
      }
    }
    mint ans=0;
    ans+=L[n-1]+R[n-1]+U[n-1];
    cout<<ans.val()<<endl;
}