#[allow(unused_imports)]
use std::cmp::*;
#[allow(unused_imports)]
use std::collections::*;
use std::io::{Write, BufWriter};
// https://qiita.com/tanakh/items/0ba42c7ca36cd29d0ac8
macro_rules! input {
    ($($r:tt)*) => {
        let stdin = std::io::stdin();
        let mut bytes = std::io::Read::bytes(std::io::BufReader::new(stdin.lock()));
        let mut next = move || -> String{
            bytes
                .by_ref()
                .map(|r|r.unwrap() as char)
                .skip_while(|c|c.is_whitespace())
                .take_while(|c|!c.is_whitespace())
                .collect()
        };
        input_inner!{next, $($r)*}
    };
}

macro_rules! input_inner {
    ($next:expr) => {};
    ($next:expr, ) => {};

    ($next:expr, $var:ident : $t:tt $($r:tt)*) => {
        let $var = read_value!($next, $t);
        input_inner!{$next $($r)*}
    };
}

macro_rules! read_value {
    ($next:expr, ( $($t:tt),* )) => {
        ( $(read_value!($next, $t)),* )
    };

    ($next:expr, [ $t:tt ; $len:expr ]) => {
        (0..$len).map(|_| read_value!($next, $t)).collect::<Vec<_>>()
    };

    ($next:expr, chars) => {
        read_value!($next, String).chars().collect::<Vec<char>>()
    };

    ($next:expr, usize1) => {
        read_value!($next, usize) - 1
    };

    ($next:expr, [ $t:tt ]) => {{
        let len = read_value!($next, usize);
        (0..len).map(|_| read_value!($next, $t)).collect::<Vec<_>>()
    }};

    ($next:expr, $t:ty) => {
        $next().parse::<$t>().expect("Parse error")
    };
}

#[allow(unused)]
macro_rules! debug {
    ($($format:tt)*) => (write!(std::io::stderr(), $($format)*).unwrap());
}
#[allow(unused)]
macro_rules! debugln {
    ($($format:tt)*) => (writeln!(std::io::stderr(), $($format)*).unwrap());
}

const MOD: i64 = 998_244_353;

fn solve() {
    let out = std::io::stdout();
    let mut out = BufWriter::new(out.lock());
    macro_rules! puts {
        ($($format:tt)*) => (write!(out,$($format)*).unwrap());
    }
    input! {
        n: usize,
        s: chars,
    }
    let get_idx = |c| ['R', 'G', 'B'].iter().position(|&a| a == c).unwrap();
    let mut cols = vec![vec![]; 3];
    let mut ans = 1;
    for (i, &c) in s.iter().enumerate() {
        let idx = get_idx(c);
        cols[idx].push(i);
    }
    let mut mark = vec![0; 3 * n];
    for i in 0..n {
        let mut u = [0; 3];
        for j in 0..3 {
            u[j] = cols[j][i];
        }
        u.sort();
        mark[u[0]] = 1;
        mark[u[2]] = 2;
    }
    // debugln!("mark = {:?}", mark);
    let mut cnt = 0;
    for i in 0..3 * n {
        match mark[i] {
            0 => {
                ans = ans * (cnt as i64) % MOD;
                cnt -= 1;
            }
            1 => cnt += 1,
            2 => (),
            _ => unreachable!(),
        }
    }
    assert_eq!(cnt, 0);
    for i in (0..3 * n).rev() {
        match mark[i] {
            0 => {
                ans = ans * (cnt as i64) % MOD;
                cnt -= 1;
            }
            2 => cnt += 1,
            1 => (),
            _ => unreachable!(),
        }
    }
    for i in 0..n {
        ans = ans * (i + 1) as i64 % MOD;
    }
    puts!("{}\n", ans);
}

fn main() {
    // In order to avoid potential stack overflow, spawn a new thread.
    let stack_size = 104_857_600; // 100 MB
    let thd = std::thread::Builder::new().stack_size(stack_size);
    thd.spawn(|| solve()).unwrap().join().unwrap();
}


Measured memory_bytes: 18024