#include <bits/stdc++.h>
#include <atcoder/all>
using namespace atcoder;
using namespace std;
#define rep(i, n) for (ll i = 0; i < (ll)(n); i++)
#define rep2(i, k, n) for (ll i = (ll)(k); i < (ll)(n); i++)
#define repM(i, k, n) for (ll i = (ll)(k); i > (ll)(n); i--)
#define all(v) v.begin(), v.end()
using ll = long long;
ll mod = 998244353;

int main() {
  ll N, ans = 0;
  string S;
  cin >> N >> S;
  // map<char, ll> M;
  // M['L'] = 0, M['R'] = 1, M['L'] = 2;
  vector<vector<ll>> dp(N, vector<ll> (3));

  rep(i, N-1){
    if(S.substr(i, 2) == "RL"){
      cout << 0;
      return 0;
    }
  }
  rep(i, 3){
    dp[0][i] = 1;
    if(S[0] == 'L'){
      dp[0][0] = 0; 
    } else if(S[0] == 'R'){
      dp[0][1] = 0; 
    } else if(S[0] == 'U'){
      dp[0][2] = 0; 
    }
  }
  rep2(i, 1, N){
    if(S[i] == 'L'){
      dp[i][0] = dp[i-1][0] + dp[i-1][2];
      dp[i][1] = 0;
      dp[i][2] = 0; 
    } else if(S[i] == 'R'){
      dp[i][0] = 0;
      dp[i][1] = ((dp[i-1][0] + dp[i-1][1]) % mod + dp[i-1][2]) % mod;
      dp[i][2] = 0; 
    } else if(S[i] == 'U'){
      dp[i][0] = 0;
      dp[i][1] = 0;
      dp[i][2] = ((dp[i-1][0] + dp[i-1][1]) % mod + dp[i-1][2]) % mod;
    } else {
      dp[i][0] = dp[i-1][0] + dp[i-1][2];
      dp[i][1] = ((dp[i-1][0] + dp[i-1][1]) % mod + dp[i-1][2]) % mod;
      dp[i][2] = ((dp[i-1][0] + dp[i-1][1]) % mod + dp[i-1][2]) % mod;
    }
    rep(k, 3){
      dp[i][k] %= mod;
    }
  }

  cout << ((dp[N-1][0] + dp[N-1][1] % mod) + dp[N-1][2]) % mod;
}