#!/usr/bin/env PyPy3

from collections import Counter, defaultdict, deque
import itertools
import re
import math
from functools import reduce
import operator
import bisect
from heapq import *
import functools
mod=998244353

import sys
input=sys.stdin.readline
#nCrをmodで割ったあまりを求める
def cmb(n, r):
    if ( r<0 or r>n ):
        return 0
    r = min(r, n-r)
    return g1[n] * g2[r] % mod * g2[n-r] % mod

N = 3 * 10 ** 5
g1 = [1, 1] # 元テーブル
g2 = [1, 1] #逆元テーブル
inverse = [0, 1] #逆元テーブル計算用テーブル

for i in range( 2, N + 1 ):
    g1.append( ( g1[-1] * i ) % mod )
    inverse.append( ( -inverse[mod % i] * (mod//i) ) % mod )
    g2.append( (g2[-1] * inverse[-1]) % mod )
n = int(input())
s = input().rstrip()
ab = 0
cd = 0
for i in range(n):
    if s[i] == 'A' or s[i] == 'B':
        ab += 1
    else:
        cd += 1
ans = cmb(ab+cd,cd)
print(ans)