#include #ifdef LOCAL #include #else #define debug(...) void(0) #endif using namespace std; typedef long long ll; #define all(x) begin(x), end(x) constexpr int INF = (1 << 30) - 1; constexpr long long IINF = (1LL << 60) - 1; constexpr int dx[4] = {1, 0, -1, 0}, dy[4] = {0, 1, 0, -1}; template istream& operator>>(istream& is, vector& v) { for (auto& x : v) is >> x; return is; } template ostream& operator<<(ostream& os, const vector& v) { auto sep = ""; for (const auto& x : v) os << exchange(sep, " ") << x; return os; } template bool chmin(T& x, U&& y) { return y < x and (x = forward(y), true); } template bool chmax(T& x, U&& y) { return x < y and (x = forward(y), true); } template void mkuni(vector& v) { sort(begin(v), end(v)); v.erase(unique(begin(v), end(v)), end(v)); } template int lwb(const vector& v, const T& x) { return lower_bound(begin(v), end(v), x) - begin(v); } int main() { ios::sync_with_stdio(false); cin.tie(nullptr); int N; cin >> N; vector X(N), Y(N); for (int i = 0; i < N; i++) cin >> X[i] >> Y[i]; int ans = 0; for (int i = 0; i < N; i++) { map, int> mp; for (int j = 0; j < N; j++) { if (i == j) continue; ll x = X[j] - X[i], y = Y[j] - Y[i]; ll g = gcd(x, y); mp[{x / g, y / g}]++; } bool ok = false; for (auto [key, val] : mp) { if (val >= 2) { ok = true; } } ans += ok; } cout << ans << '\n'; return 0; }