import java.io.*;
import java.util.*;

public class Main {
    static final int MOD = 998244353;
    public static void main(String[] args) throws Exception {
        Scanner sc = new Scanner();
        int n = sc.nextInt();
        int ab = 0;
        for (char c : sc.next().toCharArray()) {
            if (c == 'A' || c == 'B') {
                ab++;
            }
        }
        long ans = fact(n);
        ans *= pow(fact(n - ab), MOD - 2);
        ans %= MOD;
        ans *= pow(fact(ab), MOD - 2);
        ans %= MOD;
        System.out.println(ans);
    }
    
    static long fact(int x) {
        if (x == 0) {
            return 1;
        } else {
            return fact(x - 1) * x % MOD;
        }
    }
    
    static long pow(long x, int p) {
        if (p == 0) {
            return 1;
        } else if (p % 2 == 0) {
            return pow(x * x % MOD, p / 2);
        } else {
            return pow(x, p - 1) * x % MOD;
        }
    }
}

class Scanner {
    BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
    StringTokenizer st = new StringTokenizer("");
    
    public Scanner() throws Exception {
        
    }
    
    public int nextInt() throws Exception {
        return Integer.parseInt(next());
    }
    
    public long nextLong() throws Exception {
        return Long.parseLong(next());
    }
    
    public double nextDouble() throws Exception {
        return Double.parseDouble(next());
    }
    
    public String next() throws Exception {
        while (!st.hasMoreTokens()) {
            st = new StringTokenizer(br.readLine());
        }
        return st.nextToken();
    }
}