#![allow(dead_code, unused_imports, unused_macros, non_snake_case)]

fn main() {
    input! {
        N: usize,
        S: Chars,
    }

    // U L R
    let mut dp = [0i64; 3];
    dp[0] = 1;

    for i in 0 .. N {
        let mut dp_next = [0i64; 3];
        let c = S[i];
        let [u, l, r] = dp;
        
        // U
        if c == 'U' || c == '.' {
            dp_next[0] += u + l + r;
        }

        // L
        if c == 'L' || c == '.' {
            dp_next[1] += u + l;
        }

        // R
        if c == 'R' || c == '.' {
            dp_next[2] += u + l + r;
        }

        for x in &mut dp_next {
            *x %= MOD;
        }

        dp = dp_next;
    }

    println!("{}", dp.iter().sum::<i64>() % MOD);
}

type Int = i64;
const MOD: Int = 998244353;
const INF: Int = 1_000_000_000;
const YESNO: [&'static str; 2] = ["Yes", "No"];

use proconio::{input, source::line::LineSource, marker::{Usize1, Chars}};

fn yes() { println!("{}", YESNO[0]); }
fn no() { println!("{}", YESNO[1]); }
fn yesno(c: bool) { println!("{}", if c { YESNO[0] } else { YESNO[1] }); }