#include #define rep(i,s,n) for(int i = int(s); i < int(n); i++) #define all(v) (v).begin(), (v).end() using i64 = std::int64_t; template void arg_sort_ll(std::vector> &a) { using Point = std::pair; int n = (int)a.size(); std::vector ps(4, std::vector()); auto idx = [](Point v) -> int { if (v.second >= 0) return (v.first >= 0) ? 0 : 1; else return (v.first >= 0) ? 3 : 2; }; for (auto p : a) { assert(!(p.first == 0 && p.second == 0)); ps[idx(p)].emplace_back(p); } a.clear(); a.reserve(n); for (int j = 0; j < 4; j++) { int i = (3 + j) % 4; std::sort(ps[i].begin(), ps[i].end(), [](Point &p1, Point &p2) -> bool { T flag = p1.first * p2.second - p2.first * p1.second; return flag == 0 ? (p1.first * p1.first + p1.second * p1.second < p2.first * p2.first + p2.second * p2.second) : flag > 0; }); for (auto &p : ps[i]) a.emplace_back(p); } return; } template bool chmin(T &a, T b) { if(a < b) return false; a = b; return true; } int main() { std::cout << std::fixed << std::setprecision(15); int n; i64 h; std::cin >> n >> h; std::vector> ps(n); std::vector xs; for(auto &[x, y]: ps) { std::cin >> x >> y; xs.emplace_back(x); } std::sort(all(xs)); xs.erase(std::unique(all(xs)), xs.end()); std::vector arg_ord; { std::vector> ret; std::map, int> map; rep(i,0,n) { auto [x, y] = ps[i]; ret.emplace_back(2 * x, 2 * y - h); map[{2 * x, 2 * y - h}] = i; } arg_sort_ll(ret); for(auto [x, y]: ret) { arg_ord.emplace_back(map[{x, y}]); } } using ld = double; ld ans = std::numeric_limits::max(); auto calc_score = [](const std::vector &a) -> ld { if(a[2] == 0) { // assert(a[1] == 0 && a[2] == 0); return 0; } return ld(a[0]) - ld(a[1] * a[1]) / ld(4 * a[2]); }; for(auto tx: xs) { std::vector u(3, 0), d(3, 0); for(auto [x, y]: ps) { if(x <= tx) { u[0] += (y - h) * (y - h); u[1] += -2 * x * (y - h); u[2] += x * x; } else { d[0] += y * y; d[1] += -2 * x * y; d[2] += x * x; } } chmin(ans, calc_score(u) + calc_score(d)); for(auto i: arg_ord) { auto [x, y] = ps[i]; if(x <= tx) { u[0] -= (y - h) * (y - h); u[1] -= -2 * x * (y - h); u[2] -= x * x; d[0] += y * y; d[1] += -2 * x * y; d[2] += x * x; } else { d[0] -= y * y; d[1] -= -2 * x * y; d[2] -= x * x; u[0] += (y - h) * (y - h); u[1] += -2 * x * (y - h); u[2] += x * x; } chmin(ans, calc_score(u) + calc_score(d)); } } std::cout << ans << '\n'; }