N = int(input())
S = input()

P = 998244353

a = 0
b = 0
for s in S:
    if s == "A" or s == "B":
        a += 1
    else:
        b += 1
C = N + 5
fact = [1] * C
fact_inv = [1] * C
for i in range(2,C):
    fact[i] = fact[i-1] * i % P
fact_inv[-1] = pow(fact[-1],P-2,P)
for i in range(C - 2,0,-1):
    fact_inv[i] = fact_inv[i + 1] * (i + 1) % P
ans = fact[N] * fact_inv[a] % P * fact_inv[b] % P
print(ans)