//#include <monsterenergy>
#include <bits/stdc++.h>
using namespace std;
#include <atcoder/all>
using namespace atcoder;
using mint = modint998244353;
typedef long long ll;
#define all(x) (x).begin(), (x).end()
#define rall(x) (x).rbegin(), (x).rend()
const int MAX = 1e9;
const int MIN = -1*1e9;
const ll MAXLL = 1e18;
const ll MINLL = -1*1e18;

int main()
{
    int N; cin >> N;
    string S; cin >> S;
    vector<vector<mint>> DP(N+1,vector<mint>(4));
    DP[0][0] = 1;
    for(int i = 0; i < N; i++)
    {
        if(S[i] == 'L' || S[i] == '.') DP[i+1][1] = DP[i][0]+DP[i][1]+DP[i][3];
        if(S[i] == 'R' || S[i] == '.') DP[i+1][2] = DP[i][0]+DP[i][1]+DP[i][2]+DP[i][3];
        if(S[i] == 'U' || S[i] == '.') DP[i+1][3] = DP[i][0]+DP[i][1]+DP[i][2]+DP[i][3];
    }
    cout << (DP[N][1]+DP[N][2]+DP[N][3]).val() << endl;
    return 0;
}