#ifndef HIDDEN_IN_VS // 折りたたみ用 // 警告の抑制 #define _CRT_SECURE_NO_WARNINGS // ライブラリの読み込み #include using namespace std; // 型名の短縮 using ll = long long; // -2^63 ~ 2^63 = 9 * 10^18(int は -2^31 ~ 2^31 = 2 * 10^9) using pii = pair; using pll = pair; using pil = pair; using pli = pair; using vi = vector; using vvi = vector; using vvvi = vector; using vvvvi = vector; using vl = vector; using vvl = vector; using vvvl = vector; using vvvvl = vector; using vb = vector; using vvb = vector; using vvvb = vector; using vc = vector; using vvc = vector; using vvvc = vector; using vd = vector; using vvd = vector; using vvvd = vector; template using priority_queue_rev = priority_queue, greater>; using Graph = vvi; // 定数の定義 const double PI = acos(-1); const vi DX = { 1, 0, -1, 0 }; // 4 近傍(下,右,上,左) const vi DY = { 0, 1, 0, -1 }; int INF = 1001001001; ll INFL = 4004004003104004004LL; // (int)INFL = 1010931620; double EPS = 1e-15; // 入出力高速化 struct fast_io { fast_io() { cin.tie(nullptr); ios::sync_with_stdio(false); cout << fixed << setprecision(18); } } fastIOtmp; // 汎用マクロの定義 #define all(a) (a).begin(), (a).end() #define sz(x) ((int)(x).size()) #define lbpos(a, x) (int)distance((a).begin(), std::lower_bound(all(a), x)) #define ubpos(a, x) (int)distance((a).begin(), std::upper_bound(all(a), x)) #define Yes(b) {cout << ((b) ? "Yes\n" : "No\n");} #define rep(i, n) for(int i = 0, i##_len = int(n); i < i##_len; ++i) // 0 から n-1 まで昇順 #define repi(i, s, t) for(int i = int(s), i##_end = int(t); i <= i##_end; ++i) // s から t まで昇順 #define repir(i, s, t) for(int i = int(s), i##_end = int(t); i >= i##_end; --i) // s から t まで降順 #define repe(v, a) for(const auto& v : (a)) // a の全要素(変更不可能) #define repea(v, a) for(auto& v : (a)) // a の全要素(変更可能) #define repb(set, d) for(int set = 0; set < (1 << int(d)); ++set) // d ビット全探索(昇順) #define repp(a) sort(all(a)); for(bool a##_perm = true; a##_perm; a##_perm = next_permutation(all(a))) // a の順列全て(昇順) #define smod(n, m) ((((n) % (m)) + (m)) % (m)) // 非負mod #define uniq(a) {sort(all(a)); (a).erase(unique(all(a)), (a).end());} // 重複除去 #define EXIT(a) {cout << (a) << endl; exit(0);} // 強制終了 #define inQ(x, y, u, l, d, r) ((u) <= (x) && (l) <= (y) && (x) < (d) && (y) < (r)) // 半開矩形内判定 // 汎用関数の定義 template inline ll pow(T n, int k) { ll v = 1; rep(i, k) v *= n; return v; } template inline bool chmax(T& M, const T& x) { if (M < x) { M = x; return true; } return false; } // 最大値を更新(更新されたら true を返す) template inline bool chmin(T& m, const T& x) { if (m > x) { m = x; return true; } return false; } // 最小値を更新(更新されたら true を返す) template inline T get(T set, int i) { return (set >> i) & T(1); } // 演算子オーバーロード template inline istream& operator>>(istream& is, pair& p) { is >> p.first >> p.second; return is; } template inline istream& operator>>(istream& is, vector& v) { repea(x, v) is >> x; return is; } template inline vector& operator--(vector& v) { repea(x, v) --x; return v; } template inline vector& operator++(vector& v) { repea(x, v) ++x; return v; } #endif // 折りたたみ用 #if __has_include() #include using namespace atcoder; #ifdef _MSC_VER #include "localACL.hpp" #endif //using mint = modint1000000007; using mint = modint998244353; //using mint = modint; // mint::set_mod(m); namespace atcoder { inline istream& operator>>(istream& is, mint& x) { ll x_; is >> x_; x = x_; return is; } inline ostream& operator<<(ostream& os, const mint& x) { os << x.val(); return os; } } using vm = vector; using vvm = vector; using vvvm = vector; using vvvvm = vector; #endif #ifdef _MSC_VER // 手元環境(Visual Studio) #include "local.hpp" #else // 提出用(gcc) inline int popcount(int n) { return __builtin_popcount(n); } inline int popcount(ll n) { return __builtin_popcountll(n); } inline int lsb(int n) { return n != 0 ? __builtin_ctz(n) : -1; } inline int lsb(ll n) { return n != 0 ? __builtin_ctzll(n) : -1; } inline int msb(int n) { return n != 0 ? (31 - __builtin_clz(n)) : -1; } inline int msb(ll n) { return n != 0 ? (63 - __builtin_clzll(n)) : -1; } inline int msb(__int128 n) { return (n >> 64) != 0 ? (127 - __builtin_clzll((ll)(n >> 64))) : n != 0 ? (63 - __builtin_clzll((ll)(n))) : -1; } #define gcd __gcd #define dump(...) #define dumpel(v) #define dump_list(v) #define dump_mat(v) #define input_from_file(f) #define output_to_file(f) #define Assert(b) { if (!(b)) while (1) cout << "OLE"; } #endif //【有理数】 /* * Frac() : O(1) * 0 で初期化する. * * Frac(T num) : O(1) * num で初期化する. * * Frac(T num, T dnm) : O(1) * num / dnm で初期化する(分母は自動的に正にする) * * a == b, a != b, a < b, a > b, a <= b, a >= b : O(1) * 大小比較を行う(分母が共通の場合は積はとらない) * * a + b, a - b, a * b, a / b : O(1) * 加減乗除を行う(和と差については,分母が共通の場合は積はとらない) * 一方が整数でも構わない.複合代入演算子も使用可. * * reduction() : O(log min(num, dnm)) * 自身の約分を行う. * * together(Frac& a, Frac& b) : O(log min(a.dnm, b.dnm)) * a と b を通分する. * * T floor() : O(1) * 自身の floor を返す. * * T ceil() : O(1) * 自身の ceil を返す. */ template struct Frac { // verify : https://atcoder.jp/contests/abc057/tasks/abc057_d // 分子,分母 T num, dnm; // コンストラクタ Frac() : num(0), dnm(1) {} Frac(T num) : num(num), dnm(1) {} Frac(T num_, T dnm_) : num(num_), dnm(dnm_) { // verify : https://atcoder.jp/contests/abc244/tasks/abc244_h Assert(dnm != 0); if (dnm < 0) { num *= -1; dnm *= -1; } } // 代入 Frac(const Frac& b) = default; Frac& operator=(const Frac& b) = default; // キャスト operator double() const { return (double)num / dnm; } // 比較 bool operator==(const Frac& b) const { // 分母が等しいときはオーバーフロー防止のために掛け算はせず比較する. if (dnm == b.dnm) return num == b.num; return num * b.dnm == b.num * dnm; } bool operator!=(const Frac& b) const { return !(*this == b); } bool operator<(const Frac& b) const { // verify : https://atcoder.jp/contests/abc308/tasks/abc308_c // 分母が等しいときはオーバーフロー防止のために掛け算はせず比較する. if (dnm == b.dnm) return num < b.num; return (num * b.dnm < b.num * dnm); } bool operator>=(const Frac& b) const { return !(*this < b); } bool operator>(const Frac& b) const { return b < *this; } bool operator<=(const Frac& b) const { return !(*this > b); } // 整数との比較 bool operator==(T b) const { return num == b * dnm; } bool operator!=(T b) const { return num != b * dnm; } bool operator<(T b) const { return num < b * dnm; } bool operator>=(T b) const { return num >= b * dnm; } bool operator>(T b) const { return num > b * dnm; } bool operator<=(T b) const { return num <= b * dnm; } friend bool operator==(T a, const Frac& b) { return a * b.dnm == b.num; } friend bool operator!=(T a, const Frac& b) { return a * b.dnm != b.num; } friend bool operator<(T a, const Frac& b) { return a * b.dnm < b.num; } friend bool operator>=(T a, const Frac& b) { return a * b.dnm >= b.num; } friend bool operator>(T a, const Frac& b) { return a * b.dnm > b.num; } friend bool operator<=(T a, const Frac& b) { return a * b.dnm <= b.num; } // 四則演算 Frac& operator+=(const Frac& b) { // verify : https://www.codechef.com/problems/ARCTR // 分母が等しいときはオーバーフロー防止のために掛け算はせず加算する. if (dnm == b.dnm) num += b.num; else { num = num * b.dnm + b.num * dnm; dnm *= b.dnm; } return *this; } Frac& operator-=(const Frac& b) { // verify : https://www.codechef.com/problems/ARCTR // 分母が等しいときはオーバーフロー防止のために掛け算はせず加算する. if (dnm == b.dnm) num -= b.num; else { num = num * b.dnm - b.num * dnm; dnm *= b.dnm; } return *this; } Frac& operator*=(const Frac& b) { num *= b.num; dnm *= b.dnm; return *this; } Frac& operator/=(const Frac& b) { // verify : https://atcoder.jp/contests/abc301/tasks/abc301_g Assert(b.num != 0); num *= b.dnm; dnm *= b.num; if (dnm < 0) { num *= -1; dnm *= -1; } return *this; } Frac operator+(const Frac& b) const { Frac a = *this; return a += b; } Frac operator-(const Frac& b) const { Frac a = *this; return a -= b; } Frac operator*(const Frac& b) const { Frac a = *this; return a *= b; } Frac operator/(const Frac& b) const { Frac a = *this; return a /= b; } Frac operator-() const { return Frac(*this) *= Frac(-1); } // 整数との四則演算 Frac& operator+=(T c) { num += dnm * c; return *this; } Frac& operator-=(T c) { num -= dnm * c; return *this; } Frac& operator*=(T c) { num *= c; return *this; } Frac& operator/=(T c) { Assert(c != T(0)); dnm *= c; if (dnm < 0) { num *= -1; dnm *= -1; } return *this; } Frac operator+(T c) const { Frac a = *this; return a += c; } Frac operator-(T c) const { Frac a = *this; return a -= c; } Frac operator*(T c) const { Frac a = *this; return a *= c; } Frac operator/(T c) const { Frac a = *this; return a /= c; } friend Frac operator+(T c, const Frac& a) { return a + c; } friend Frac operator-(T c, const Frac& a) { return Frac(c) - a; } friend Frac operator*(T c, const Frac& a) { return a * c; } friend Frac operator/(T c, const Frac& a) { return Frac(c) / a; } // 約分を行う. void reduction() { // verify : https://atcoder.jp/contests/abc229/tasks/abc229_h auto g = gcd(abs(num), abs(dnm)); num /= g; dnm /= g; } // a と b を通分する. friend void together(Frac& a, Frac& b) { // verify : https://atcoder.jp/contests/abc229/tasks/abc229_h T dnm = a.dnm / gcd(a.dnm, b.dnm) * b.dnm; a.num *= dnm / a.dnm; a.dnm = dnm; b.num *= dnm / b.dnm; b.dnm = dnm; } // 自身の floor を返す. T floor() const { // verify : https://www.codechef.com/problems/LINEFIT?tab=statement if (num >= 0) return num / dnm; else return -((-num + dnm - 1) / dnm); } // 自身の ceil を返す. T ceil() const { // verify : https://www.codechef.com/problems/LINEFIT?tab=statement if (num >= 0) return (num + dnm - 1) / dnm; else return -((-num) / dnm); } #ifdef _MSC_VER friend ostream& operator<<(ostream& os, const Frac& a) { os << a.num << '/' << a.dnm; return os; } #endif }; #ifdef _MSC_VER #define __int128 ll // デバッグ用 #endif int main() { // input_from_file("input.txt"); // output_to_file("output.txt"); int n; ll h; cin >> n >> h; vl x(n), y(n); rep(i, n) cin >> x[i] >> y[i]; if (n <= 2) EXIT(0); vector, int>> uid(n), vid(n); rep(i, n) { uid[i] = { Frac<__int128>(2 * y[i] - h, x[i]), i }; vid[i] = { Frac<__int128>(h, x[i]), i }; } uid.push_back({ Frac<__int128>(-INF, 1), -1 }); vid.push_back({ Frac<__int128>(-INF, 1), -1 }); sort(all(uid)); sort(all(vid)); //repi(i, 1, n) cerr << "(" << (double)uid[i].first << "," << uid[i].second << ") "; //cerr << endl; //repi(i, 1, n) cerr << "(" << (double)vid[i].first << "," << vid[i].second << ") "; //cerr << endl; vi tp0(n, 0); double res = (double)INFL; rep(i, n + 1) { auto [u, id] = uid[i]; if (id != -1) { tp0[id] ^= 1; } auto tp(tp0); // a0 + a1 a = 0, b0 + b1 b = 0 ll a0 = 0, a1 = 0, b0 = 0, b1 = 0; rep(id, n) { if (tp[id] == 0) { a1 += 2 * x[id] * x[id]; a0 += -2 * x[id] * y[id] + 2 * h * x[id]; } else { b1 += 2 * x[id] * x[id]; b0 += -2 * x[id] * y[id]; } } rep(j, n + 1) { auto [v, id] = vid[j]; dump("---", i, (double)u, j, (double)v, "---"); if (id != -1) { if (tp[id] == 0) { a1 -= 2 * x[id] * x[id]; a0 -= -2 * x[id] * y[id] + 2 * h * x[id]; b1 += 2 * x[id] * x[id]; b0 += -2 * x[id] * y[id]; } else { a1 += 2 * x[id] * x[id]; a0 += -2 * x[id] * y[id] + 2 * h * x[id]; b1 -= 2 * x[id] * x[id]; b0 -= -2 * x[id] * y[id]; } tp[id] ^= 1; } dump("tp:", tp); if (a1 == 0 || b1 == 0) continue; Frac<__int128> a(-a0, a1), b(-b0, b1); dump("a:", (double)a, "b:", (double)b); bool ok = true; if (i >= 0 && uid[i].first > b + a) ok = false; if (i < n && uid[i + 1].first < b + a) ok = false; if (j >= 0 && vid[j].first > b - a) ok = false; if (j < n && vid[j + 1].first < b - a) ok = false; if (!ok) continue; double val = 0; rep(k, n) { double val_a = pow((double)(y[k] - a * x[k] - h), 2.); double val_b = pow((double)(y[k] - b * x[k]), 2.); val += min(val_a, val_b); } dump("val:", val); chmin(res, val); } } cout << (double)res << endl; }