/* -*- coding: utf-8 -*-
 *
 * 1481.cc:  No.1481 Rotation ABC - yukicoder
 */

#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<cmath>
#include<iostream>
#include<string>
#include<vector>
#include<map>
#include<set>
#include<stack>
#include<list>
#include<queue>
#include<deque>
#include<algorithm>
#include<numeric>
#include<utility>
#include<complex>
#include<functional>
 
using namespace std;

/* constant */

const int MAX_N = 100000;
const int MOD = 998244353;

/* typedef */

typedef long long ll;
typedef vector<int> vi;
typedef queue<int> qi;
typedef pair<int,int> pii;

/* global variables */

char s[MAX_N + 4];
int cs[3], rs[3], fs[MAX_N + 1];

/* subroutines */

int powmod(int a, int n) {  // a^n % MOD
  int pm = 1;
  while (n > 0) {
    if (n & 1) pm = (ll)pm * a % MOD;
    a = (ll)a * a % MOD;
    n >>= 1;
  }
  return pm;
}

/* main */

int main() {
  int n;
  scanf("%d%s", &n, s);

  for (int i = 0; i < n; i++) {
    int si = s[i] - 'A';
    cs[si]++;
    rs[si] = max(rs[si], rs[(si + 2) % 3] + 1);
  }

  if (rs[0] >= 3 || rs[1] >= 3 || rs[2] >= 3) {
    fs[0] = 1;
    for (int i = 1; i <= n; i++) fs[i] = (ll)fs[i - 1] * i % MOD;

    int s = fs[n];
    for (int i = 0; i < 3; i++)
      s = (ll)s * powmod(fs[cs[i]], MOD - 2) % MOD;

    s = (s + MOD - n) % MOD;

    printf("%d\n", s);
  }
  else
    puts("1");
  return 0;
}