MOD = 998244353

n = int(input())
s = input().strip()

a = s.count('A')
b = s.count('B')
c_count = s.count('C')
d_count = s.count('D')

ab_count = a + b
cd_count = c_count + d_count

if ab_count > 0 and cd_count > 0:
    max_n = n
    fact = [1] * (max_n + 1)
    for i in range(1, max_n + 1):
        fact[i] = fact[i-1] * i % MOD
    
    inv_fact = [1] * (max_n + 1)
    inv_fact[max_n] = pow(fact[max_n], MOD-2, MOD)
    for i in range(max_n - 1, -1, -1):
        inv_fact[i] = inv_fact[i+1] * (i+1) % MOD
    
    def comb(n, k):
        if k < 0 or k > n:
            return 0
        return fact[n] * inv_fact[k] % MOD * inv_fact[n - k] % MOD
    
    ans = comb(n, ab_count)
else:
    ans = 1

print(ans)