#include <iostream>
#include <string>
#include <cmath>
#include<algorithm>
#include<stack>
#include<queue>
#include<map>
#include<set>
#include<iomanip>
#include<bitset>
#define _USE_MATH_DEFINES
#include <math.h>
#include <functional>
#include<complex>
#include<cassert>
#include<random>
using namespace std;
#include<atcoder/all>
using namespace atcoder;


#define rep(i,x) for(ll i=0;i<x;i++)
#define repn(i,x) for(ll i=1;i<=x;i++)

typedef long long ll;
typedef pair<ll, ll> P;
const ll INF = 1e17;
const ll MAX = 4000001;
const long double eps = 1E-14;

ll max(ll a, ll b) {
	if (a > b) { return a; }
	return b;
}

ll min(ll a, ll b) {
	if (a > b) { return b; }
	return a;
}

ll gcd(ll a, ll b) {
	if (b == 0) { return a; }
	if (a < b) { return gcd(b, a); }
	return gcd(b, a % b);
}

ll lcm(ll a, ll b) {
	return a / gcd(a, b) * b;
}

struct edge {
	ll id;
	ll fr;
	ll to;
	ll d;
};

using mint = modint;

typedef vector<ll> vll;
typedef vector <vector<ll>> vvll;
typedef vector<vector<vector<ll>>> vvvll;

typedef vector<mint> vmint;
typedef vector<vector<mint>> vvmint;
typedef vector<vector<vector<mint>>> vvvmint;

vmint f, finv, inv;

void cominit(ll N) {
	ll MOD = modint::mod();//デフォルトが998244353に注意

	f.assign(N + 1, 1);
	finv.assign(N + 1, 1);
	inv.assign(N + 1, 1);
	inv[1] = 1;

	repn(i, N) {
		f[i] = f[i - 1] * i;
		if (i > 1)inv[i] = -inv[MOD % i] * (MOD / i);
		finv[i] = finv[i - 1] * inv[i];
	}
}

mint com(ll a, ll b) {
	if (a < 0 || b < 0 || a < b) { return 0; }
	return f[a] * finv[b] * finv[a - b];
}


/////////////////////////////////////

bool ch(string S, string T) {
	ll t = 0;
	rep(i, S.size()) {
		if (S[i] == T[t]) { t++; }
		if (t == T.size()) { return true; }
	}

	return false;
}


int main() {
	ll N;
	cin >> N;
	string S;
	cin >> S;
	set<char> st;
	rep(i, N)st.insert(S[i]);
	if (st.size() < 3) { cout << 1 << endl; return 0; }
	if (!ch(S, "ABC") && !ch(S, "BCA") && !ch(S, "CAB")) { cout << 1 << endl; return 0; }

	cominit(N + 1);
	vll c(3);
	rep(i, N)c[S[i] - 'A']++;

	mint ans = com(N, c[0]) * com(c[1] + c[2], c[1]);
	ans -= N;
	cout << ans.val() << endl;
}