#include "bits/stdc++.h"
#include "atcoder/all"
using namespace std;
using namespace atcoder;
//using mint = modint1000000007;
//const int mod = 1000000007;
using mint = modint998244353;
const int mod = 998244353;
const int INF = 1e9;
//const long long LINF = 1e18;
#define rep(i, n) for (int i = 0; i < (n); ++i)
#define rep2(i,l,r)for(int i=(l);i<(r);++i)
#define rrep(i, n) for (int i = (n-1); i >= 0; --i)
#define rrep2(i,l,r)for(int i=(r-1);i>=(l);--i)
#define all(x) (x).begin(),(x).end()
#define allR(x) (x).rbegin(),(x).rend()
#define endl "\n"
struct combination {
	vector<mint> fact, ifact;
	combination(int n) :fact(n + 1), ifact(n + 1) {
		assert(n < mod);
		fact[0] = 1;
		for (int i = 1; i <= n; ++i) fact[i] = fact[i - 1] * i;
		ifact[n] = fact[n].inv();
		for (int i = n; i >= 1; --i) ifact[i - 1] = ifact[i] * i;
	}
	mint operator()(int n, int k) {
		return com(n, k);
	}
	mint com(int n, int k) {
		//負の二項係数を考慮する場合にコメントアウトを外す
		//if (n < 0) return com(-n, k) * (k % 2 ? -1 : 1);
		if (k < 0 || k > n) return 0;
		return fact[n] * ifact[k] * ifact[n - k];
	}
	mint inv(int n, int k) {
		//if (n < 0) return inv(-n, k) * (k % 2 ? -1 : 1);
		if (k < 0 || k > n) return 0;
		return ifact[n] * fact[k] * fact[n - k];
	}
}c(100005);
int main() {
	ios::sync_with_stdio(false);
	cin.tie(nullptr);
	int n; cin >> n;
	string s; cin >> s;
	int acount = count(all(s), 'A');
	int bcount = count(all(s), 'B');
	int ccount = count(all(s), 'C');
	if ((0 == acount) || (0 == bcount) || (0 == ccount)) {
		cout << 1 << endl;
		return 0;
	}
	string subs = s + s;
	bool b = false;
	rep(i, s.size()) {
		if ((s[i] == 'A') && (s[i + 1] == 'B')) {
			b = true;
		}
		else if ((s[i] == 'C') && (s[i + 1] == 'A')) {
			b = true;
		}
		else if ((s[i] == 'B') && (s[i + 1] == 'C')) {
			b = true;
		}
	}
	if (!b) {
		cout << 1 << endl;
		return 0;
	}
	mint ans = c.fact[acount + bcount + ccount] * c.ifact[acount] * c.ifact[bcount] * c.ifact[ccount] - n;
	cout << ans.val() << endl;
	return 0;
}