mod = 998244353
eps = 10**-9


def main():
    import sys
    input = sys.stdin.readline

    # comb init
    nmax = 10 ** 5 + 10  # change here
    fac = [0] * nmax
    finv = [0] * nmax
    inv = [0] * nmax
    fac[0] = 1
    fac[1] = 1
    finv[0] = 1
    finv[1] = 1
    inv[1] = 1
    for i in range(2, nmax):
        fac[i] = fac[i - 1] * i % mod
        inv[i] = mod - inv[mod % i] * (mod // i) % mod
        finv[i] = finv[i - 1] * inv[i] % mod

    def comb(n, r):
        if n < r:
            return 0
        else:
            return (fac[n] * ((finv[r] * finv[n - r]) % mod)) % mod

    N = int(input())
    S = input().rstrip('\n')

    ok = 0
    # ABC
    flg = 0
    for s in S:
        if flg == 0 and s == "A":
            flg = 1
        elif flg == 1 and s == "B":
            flg = 2
        elif flg == 2 and s == "C":
            ok = 1
            break

    # BCA
    flg = 0
    for s in S:
        if flg == 0 and s == "B":
            flg = 1
        elif flg == 1 and s == "C":
            flg = 2
        elif flg == 2 and s == "A":
            ok = 1
            break

    # CAB
    flg = 0
    for s in S:
        if flg == 0 and s == "C":
            flg = 1
        elif flg == 1 and s == "A":
            flg = 2
        elif flg == 2 and s == "B":
            ok = 1
            break

    if not ok:
        print(1)
        exit()

    a = S.count("A")
    b = S.count("B")
    c = N - a - b
    ans = (comb(N, a) * comb(N-a, b) - a - b - c)%mod
    print(ans)


if __name__ == '__main__':
    main()