#include <bits/stdc++.h>
#include <atcoder/all>
using namespace std;
using namespace atcoder;

constexpr int mod = 998244353;

long long power_mod(long long a, long long p) {
  if (p==0) return 1LL;
  a %= mod;
  if (a<0) a += mod;
  if (p<0) {
    assert(gcd(a,mod)==1);
    p = (p%(mod-1))+mod-1;
  }
  long long result = 1;
  long long b = a;
  while (p>0) {
    if (p&1LL) result = result*b%mod;
    b = b*b%mod;
    p >>= 1;
  }
  return result;
}

vector<long long> factorial;
vector<long long> fact_inv;
void make_factorial(int n, bool make_inv = true) {
  assert(n>=0);
  if (make_inv) assert(n<mod);
  factorial.assign(n+1,1);
  for (int i=1; i<=n; i++) {
    factorial[i] = factorial[i-1]*i%mod;
  }
  if (!make_inv) return;
  fact_inv.assign(n+1,power_mod(factorial[n],-1));
  for (int i=n; i>0; i--) {
    fact_inv[i-1] = fact_inv[i]*i%mod;
  }
}

long long comb(int n, int r) {
  if (r<0) return 0;
  if (r>n) return 0;
  long long result = factorial[n];
  result *= fact_inv[r];
  result %= mod;
  result *= fact_inv[n-r];
  result %= mod;
  return result;
}

long long comb_inv(int n, int r) {
  assert(r>=0);
  assert(r<=n);
  assert(n<mod);
  long long result = fact_inv[n];
  result *= factorial[r];
  result %= mod;
  result *= factorial[n-r];
  result %= mod;
  return result;
}

/////////////////// メイン ///////////////////

int main () {
  
  //////////////////// 入力 ////////////////////

  int n;
  string s;
  cin >> n >> s;

  //////////////// 出力変数定義 ////////////////

  int result = 0;

  //////////////////// 処理 ////////////////////

  make_factorial(n);

  int counter0 = 0;
  int counter1 = 0;
  for (char c : s) {
    if (c=='A'||c=='B') counter0++;
    else counter1++;
  }

  result = comb(counter0+counter1,counter0);

  //////////////////// 出力 ////////////////////

  cout << result << endl;

  //////////////////// 終了 ////////////////////

  return 0;

}