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

const int mod=998244353;

int main(){
  ios::sync_with_stdio(false);
  cin.tie(nullptr);
  int N;
  string S;
  cin>>N>>S;
  int AB=0,CD=0;
  vector<long long>inv(N+1),fac(N+1),invf(N+1);
  fac[0]=inv[0]=invf[0]=1;
  fac[1]=inv[1]=invf[1]=1;
  for(int i=2;i<=N;i++){
    fac[i]=fac[i-1]*i%mod;
    inv[i]=inv[mod%i]*(mod-mod/i)%mod;
    invf[i]=invf[i-1]*inv[i]%mod;
  }
  for(int i=0;i<=N;i++){
    switch(S[i]){
      case 'A':++AB;break;
      case 'B':++AB;break;
      case 'C':++CD;break;
      case 'D':++CD;break;
    }
  }
  cout<<fac[N]*invf[AB]%mod*invf[CD]%mod<<'\n';
}