use proconio::input;
use proconio::fastout;
use proconio::marker::Chars;
use ac_library::ModInt998244353 as Mint;

#[fastout]
#[allow(non_snake_case)]
fn main() {
    input! {
        N: usize,
        S: Chars,
    }
    assert!(1 <= N && N <= 200_000 && N == S.len());
    assert!(S.iter().all(|x| ['.', 'L', 'R', 'U'].contains(x)));
    let mut DP = vec![vec![Mint::new(0); 3]; N+1];
    DP[0][0] = 1.into();
    for i in 0..N {
        if S[i] == 'U' || S[i] == '.' {
            DP[i+1][0] = DP[i][0] + DP[i][1] + DP[i][2];
        }
        if S[i] == 'L' || S[i] == '.' {
            DP[i+1][1] = DP[i][0] + DP[i][1];
        }
        if S[i] == 'R' || S[i] == '.' {
            DP[i+1][2] = DP[i][0] + DP[i][1] + DP[i][2];
        }
    }
    println!("{}", DP[N][0] + DP[N][1] + DP[N][2]);
}