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

constexpr int mod = 998244353;

long long fac[2000005], finv[2000005], inv[2000005];

void COMinit() {
    fac[0] = fac[1] = finv[0] = finv[1] = inv[1] = 1;
    for (int i = 2; i < 2000005; i++) {
        fac[i] = fac[i - 1] * i % mod;
        inv[i] = mod - inv[mod % i] * (mod / i) % mod;
        finv[i] = finv[i - 1] * inv[i] % mod;
    }
}

long long COM(int n, int k){
    if (n < k) return 0;
    if (n < 0 || k < 0) return 0;
    return fac[n] * (finv[k] * finv[n - k] % mod) % mod;
}

int main() {
    int N;
    string S;
    cin >> N >> S;
    COMinit();
    int a = 0,c = 0;
    for(int i = 0; i < N; i++) {
        if(S[i] == 'A' || S[i] == 'B') {
            a++;
        }
        else {
            c++;
        }
    }
    cout << COM(N,a) << endl;
}