#include <bits/stdc++.h>
#include <atcoder/all>
using namespace std;
using namespace atcoder;
#define rep(i, n) for(int i=0;i<(n);++i)
#define rep1(i, n) for(int i=1;i<=(n);i++)
#define ll long long
using mint = modint998244353;
using P = pair<ll,ll>;
using lb = long double;
using T = tuple<ll, ll, ll>;
#ifdef LOCAL
#  include <debug_print.hpp>
#  define dbg(...) debug_print::multi_print(#__VA_ARGS__, __VA_ARGS__)
#else
#  define dbg(...) (static_cast<void>(0))
#endif

int main()
{
    int n;
    string s;
    cin >> n >> s;
    vector<mint> dp(3);
    dp[2] = 1;
    rep(i,n) {
        vector<mint> p(3);
        swap(dp, p);
        if(s[i]=='L') {
            dp[0] += (p[0]+p[2]);
        }
        else if(s[i]=='R') dp[1] += p[0] + p[1] + p[2];
        else if(s[i]=='U') dp[2] += p[0] + p[1] + p[2];
        else{
            dp[0] += (p[0]+p[2]);
            dp[1] += p[0] + p[1] + p[2];
            dp[2] += p[0] + p[1] + p[2];
        }
    }
    mint ans = 0;
    rep(i,3) ans += dp[i];
    cout << ans.val() << endl;
    return 0;
}