import java.util.Scanner;

public class Main {
	public static void main(String[] args) throws Exception {
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		char[] s = sc.next().toCharArray();
		sc.close();

		int mod = 998244353;
		long[] dpl = new long[n];
		long[] dpr = new long[n];
		long[] dpu = new long[n];
		if (s[0] == 'L' || s[0] == '.') dpl[0] = 1;
		if (s[0] == 'R' || s[0] == '.') dpr[0] = 1;
		if (s[0] == 'U' || s[0] == '.') dpu[0] = 1;
		for (int i = 1; i < n; i++) {
			if (s[i] == 'L' || s[i] == '.') {
				dpl[i] = (dpl[i - 1] + dpu[i - 1]) % mod;
			}
			if (s[i] == 'R' || s[i] == '.') {
				dpr[i] = (dpl[i - 1] + dpr[i - 1] + dpu[i - 1]) % mod;
			}
			if (s[i] == 'U' || s[i] == '.') {
				dpu[i] = (dpl[i - 1] + dpr[i - 1] + dpu[i - 1]) % mod;
			}
		}
		long ans = dpl[n - 1] + dpr[n - 1] + dpu[n - 1];
		ans %= mod;
		System.out.println(ans);
	}
}