#include <bits/stdc++.h>
using namespace std;
#define rep(i, s, t) for (auto i{s}; std::cmp_less(i, t); ++i)

#include <atcoder/modint>
typedef atcoder::modint998244353 Int;
ostream& operator<<(ostream &o, Int const &x) { return o << x.val(); }

struct DP { Int L, U, R; };

int main() {
  int N;
  string S;
  cin >> N >> S;

  vector<DP> dp(N);
  rep(i, 0, N) {
    if (i == 0) {
      dp[i].L = dp[i].U = dp[i].R = Int::raw(1);
    }
    else {
      dp[i].L = dp[i-1].L + dp[i-1].U;
      dp[i].U = dp[i-1].L + dp[i-1].U + dp[i-1].R;
      dp[i].R = dp[i-1].L + dp[i-1].U + dp[i-1].R;
    }
    if (S[i] == 'L')
      dp[i].U = dp[i].R = Int::raw(0);
    if (S[i] == 'U')
      dp[i].L = dp[i].R = Int::raw(0);
    if (S[i] == 'R')
      dp[i].L = dp[i].U = Int::raw(0);
  }

  cout << dp[N-1].L + dp[N-1].U + dp[N-1].R << endl;
}