#include <bits/stdc++.h>
#include <atcoder/all>
#define rep(i, n) for(long long i = 0; i < n; i++)
#define ALL(v) (v).begin(), (v).end()
#define rALL(v) (v).rbegin(), (v).rend()
using namespace std;

using lint = long long;
using ld = long double;
using mint = atcoder::modint998244353;

int main() {
    int n;
    string s;
    cin >> n >> s;
    rep(i, (int)s.size() - 1) {
        if (s[i] == 'R' && s[i + 1] == 'L') {
            cout << 0 << endl;
            return 0;
        }
    }
    vector<vector<mint>> dp(n, vector<mint>(3));
    if (s[0] == 'L') {
        dp[0][0] = mint(1);
    } else if (s[0] == 'R') {
        dp[0][1] = mint(1);
    } else if (s[0] == 'U') {
        dp[0][2] = mint(1);
    } else {
        dp[0][0] = dp[0][1] = dp[0][2] = mint(1);
    }
    for (int i = 1; i < n; i++) {
        if (s[i] == 'L') {
            dp[i][0] += (dp[i - 1][0] + dp[i - 1][2]);
            dp[i][1] = dp[i][2] = mint(0);
        } else if (s[i] == 'R') {
            dp[i][1] += (dp[i - 1][0] + dp[i - 1][1] + dp[i - 1][2]);
            dp[i][0] = dp[i][2] = mint(0);
        } else if (s[i] == 'U') {
            dp[i][2] += (dp[i - 1][0] + dp[i - 1][1] + dp[i - 1][2]);
            dp[i][0] = dp[i][1] = mint(0);
        } else {
            dp[i][0] += (dp[i - 1][0] + dp[i - 1][2]);
            dp[i][1] += (dp[i - 1][0] + dp[i - 1][1] + dp[i - 1][2]);
            dp[i][2] += (dp[i - 1][0] + dp[i - 1][1] + dp[i - 1][2]);
        }
    }
    /*rep(i, n) {
        rep(j, 3) {
            cout << i << " " << j << " " << dp[i][j].val() << endl;
        }
    }*/
    mint ans = accumulate(ALL(dp[n - 1]), mint(0));
    cout << ans.val() << endl;
}