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


MOD = 998244353
table_len = 10 ** 5 + 10

fac = [1, 1]
for i in range(2, table_len):
    fac.append(fac[-1] * i % MOD)

finv = [0] * table_len
finv[-1] = pow(fac[-1], MOD - 2, MOD)
for i in range(table_len-1, 0, -1):
    finv[i-1] = finv[i] * i % MOD

def comb(n, k):
    if k < 0 or n < 0 or n - k < 0:
        return 0
    return fac[n] * finv[k] % MOD * finv[n - k] % MOD


if len(S) < 3:
    print(1)
    exit()

state_abc = 0
state_bca = 0
state_cab = 0
for c in S:
    if state_abc == ord(c) - ord('A'):
        state_abc += 1
    if state_bca == (ord(c) - ord('B')) % 3:
        state_bca += 1
    if state_cab == (ord(c) - ord('C')) % 3:
        state_cab += 1
    
if 3 not in (state_abc, state_bca, state_cab):
    print(1)
    exit()

a = S.count('A')
b = S.count('B')
c = S.count('C')

ans = fac[len(S)] * finv[a] % MOD * finv[b] % MOD * finv[c] % MOD
ans -= (a + b + c)
ans %= MOD

print(ans)