#include <bits/stdc++.h>
using namespace std;

#define rep(i, n) for(int i = 0; i < n; i++ )
using ll = long long;

int main() {
	int N;
	string s;
	cin >> N >> s;
	vector<vector<ll>> dp(N + 1, vector<ll>(3));
	dp[0][0] = 1;
	ll MOD = 998244353;
	rep(i, N) {
		rep(j, 3) {
			if(s[i] == 'U') dp[i + 1][0] = (dp[i + 1][0] + dp[i][j]) % MOD;
			else if(s[i] == 'R') dp[i + 1][1] = (dp[i + 1][1] + dp[i][j]) % MOD;
			else if(s[i] == 'L') {
				if(j != 1) dp[i + 1][2] = (dp[i + 1][2] + dp[i][j]) % MOD;
			}
			else {
				rep(k, 3) {
					if(j == 1 && k == 2) continue;
					dp[i + 1][k] = (dp[i + 1][k] + dp[i][j]) % MOD;
				}
			}
		}
	}
	ll ans = 0;
	rep(i, 3) ans = (ans + dp[N][i]) % MOD;

	cout << ans << endl;
}