#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 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; }