N = int(input())
S = list(input())
mod =998244353

countab = 0
countcd = 0

for s in S:
    if s=="A" or s=="B":
        countab+=1
    else:
        countcd+=1

fac = [1]*(N+1)
rfac = [1]*(N+1)
for i in range(1,N+1):
    fac[i] = fac[i-1]*i%mod
    rfac[i] = pow(fac[i], mod-2, mod)

def comb(n, r, mod):
    return (fac[n]*rfac[r]*rfac[n-r])%mod

print(comb(N,countab,mod))