class BIT():
    def __init__(self,n,mod=0):
        self.BIT=[0]*(n+1)
        self.num=n
        self.mod = mod

    def query(self,idx):
        res_sum = 0
        while idx > 0:
            res_sum += self.BIT[idx]
            if self.mod:
                res_sum %= self.mod
            idx -= idx&(-idx)
        return res_sum

    #Ai += x O(logN)
    def update(self,idx,x):
        while idx <= self.num:
            self.BIT[idx] += x
            if self.mod:
                self.BIT[idx] %= mod
            idx += idx&(-idx)
        return

class SegmentTree:
    def __init__(self, init_val, segfunc, ide_ele):
        n = len(init_val)
        self.segfunc = segfunc
        self.ide_ele = ide_ele
        self.num = 1 << (n - 1).bit_length()
        self.tree = [ide_ele] * 2 * self.num
        for i in range(n):
            self.tree[self.num + i] = init_val[i]
        for i in range(self.num - 1, 0, -1):
            self.tree[i] = self.segfunc(self.tree[2 * i], self.tree[2 * i + 1])

    def update(self, k, x, op=False):
        k += self.num
        if not op:
            self.tree[k] = x
        else:
            self.tree[k] = self.segfunc(self.tree[k],x)
        while k > 1:
            k >>= 1
            self.tree[k] = self.segfunc(self.tree[2*k], self.tree[2*k+1])


    def query(self, l, r):
        res = self.ide_ele

        l += self.num
        r += self.num
        right = []
        while l < r:
            if l & 1:
                res = self.segfunc(res, self.tree[l])
                l += 1
            if r & 1:
                right.append(self.tree[r-1])
            l >>= 1
            r >>= 1

        for val in right[::-1]:
            res = self.segfunc(res,val)
        return res

import sys,random,bisect
from collections import deque,defaultdict
from heapq import heapify,heappop,heappush
from itertools import permutations
from math import log,gcd

input = lambda :sys.stdin.readline().rstrip()
mi = lambda :map(int,input().split())
li = lambda :list(mi())

def cmb(n, r, mod):#コンビネーションの高速計算　
    if ( r<0 or r>n ):
        return 0
    r = min(r, n-r)
    return g1[n] * g2[r] * g2[n-r] % mod

mod = 998244353 #出力の制限
N = 2*10**5
g1 = [1]*(N+1) # 元テーブル
g2 = [1]*(N+1) #逆元テーブル
inverse = [1]*(N+1) #逆元テーブル計算用テーブル

for i in range( 2, N + 1 ):
    g1[i]=( ( g1[i-1] * i ) % mod )
    inverse[i]=( ( -inverse[mod % i] * (mod//i) ) % mod )
    g2[i]=( (g2[i-1] * inverse[i]) % mod )
inverse[0]=0

N = int(input())
S = input().rstrip()

def solve(S):
    A = [i for i in range(N) if S[i]=="A"]
    B = [i for i in range(N) if S[i]=="B"]
    C = [i for i in range(N) if S[i]=="C"]
    a,b,c = len(A),len(B),len(C)

    if not a*b*c:
        return 1

    L,R = A[0],C[-1]
    for i in range(L,R):
        if S[i]=="B":
            res = g1[N]*g2[a]*g2[b]*g2[c]-N
            return res % mod
    L,R = B[0],A[-1]
    for i in range(L,R):
        if S[i]=="C":
            res = g1[N]*g2[a]*g2[b]*g2[c]-N
            return res % mod
    L,R = C[0],B[-1]
    for i in range(L,R):
        if S[i]=="A":
            res = g1[N]*g2[a]*g2[b]*g2[c]-N
            return res % mod
    return 1

print(solve(S))