n = int(input())
s = input()
x = y = 0
for i in s:
    if i == 'A' or i == 'B':
        x += 1
    if i == 'C' or i == 'D':
        y += 1
mod = 998244353
fac = [1] * (n + 1)
for i in range(n):
    fac[i + 1] = (i + 1) * fac[i] % mod
ans = fac[n] * pow(fac[x], mod - 2, mod) * pow(fac[y], mod - 2, mod)
print(ans % mod)