#include <stdio.h>
#include <bits/stdc++.h>
#include <atcoder/all>
using namespace atcoder;
using mint = modint998244353;
using namespace std;
#define rep(i,n) for (int i = 0; i < (n); ++i)
#define Inf 1000000001

bool check(string S){
	vector<int> dp(4,0);
	dp[0] = 1;
	
	rep(i,S.size()){
		int x = S[i]-'A';
		x++;
		dp[x] |= dp[x-1];
	}
	return dp.back();
}

struct combi{
	deque<mint> kaijou;
	deque<mint> kaijou_;
	
	combi(int n){
		kaijou.push_back(1);
		for(int i=1;i<=n;i++){
			kaijou.push_back(kaijou[i-1]*i);
		}
		
		mint b=kaijou[n].inv();
		
		kaijou_.push_front(b);
		for(int i=1;i<=n;i++){
			int k=n+1-i;
			kaijou_.push_front(kaijou_[0]*k);
		}
	}
	
	mint combination(int n,int r){
		if(r>n)return 0;
		mint a = kaijou[n]*kaijou_[r];
		a *= kaijou_[n-r];
		return a;
	}
	
	mint junretsu(int a,int b){
		mint x = kaijou_[a]*kaijou_[b];
		x *= kaijou[a+b];
		return x;
	}
	
	mint catalan(int n){
		return combination(2*n,n)/(n+1);
	}
	
};

int main(){
	
	int N;
	cin>>N;
	
	string S;
	cin>>S;
	
	bool f = false;
	
	rep(_,3){
		
		if(check(S))f=true;
		
		rep(i,N){
			S[i]++;
			if(S[i]=='D')S[i] = 'A';
		}
	}
	
	if(!f){
		cout<<1<<endl;
		return 0;
	}
	
	combi C(1000000);
	
	vector<int> cnt(3,0);
	rep(i,S.size()){
		cnt[S[i]-'A']++;
	}
	
	mint ans = C.kaijou[N];
	ans /= C.kaijou[cnt[0]];
	ans /= C.kaijou[cnt[1]];
	ans /= C.kaijou[cnt[2]];
	
	ans -= N;
	
	cout<<ans.val()<<endl;
	
    return 0;
}