#include using namespace std; #include using namespace atcoder; using ll = long long; using ld = long double; using P = pair; using Graph = vector>; using vi = vector; using vl = vector; using vll = vector; using vvi = vector; using vvl = vector; using vvll = vector; using vs = vector; using vc = vector; using vvc = vector; using pll = pair; using vpll = vector; using mint = modint1000000007; const long double EPS = 1e-18; const long long INF = 1e18; const long double PI = acos(-1.0L); #define reps(i, a, n) for (ll i = (a); i < (ll)(n); i++) #define rep(i, n) for (ll i = (0); i < (ll)(n); i++) #define rrep(i, n) for (ll i = (1); i < (ll)(n + 1); i++) #define repd(i, n) for (ll i = n - 1; i >= 0; i--) #define rrepd(i, n) for (ll i = n; i >= 1; i--) #define ALL(n) begin(n), end(n) #define IN(a, x, b) (a <= x && x < b) #define INIT \ std::ios::sync_with_stdio(false); \ std::cin.tie(0); template inline T CHMAX(T& a, const T b) { return a = (a < b) ? b : a; } template inline T CHMIN(T& a, const T b) { return a = (a > b) ? b : a; } int main() { int N; string S; cin >> N >> S; set> ret; rep(i, N - 1) { vector v; rep(d, 2) { if (S[i + d] == 'A') v.push_back(i + d); } ret.insert(v); } cout << ret.size() << endl; }