#include<bits/stdc++.h>
using std::cin, std::cout;
const int N = 1000005;
using u64 = unsigned long long;
int n;
using db = double;
const db eps = 1e-8;
const db pi = std::acos(-1);
db sgn(db x) { return x < -eps ? -1 : x > eps; }
db eq(db x, db y) { return !sgn(x - y); }
struct p2 {
	db x, y;

	db norm() const { return x * x + y * y; }
	db abs() const { return std::sqrt(x * x + y * y); }
	db arg() const { return atan2(y, x); }
};
db arg(p2 x, p2 y) {
	db a = y.arg() - x.arg();
	if(a > pi) a -= pi * 2;
	if(a < -pi) a += pi * 2;
	return a;
}
p2 r90(p2 x) { return {-x.y, x.x}; }
p2 operator + (p2 x, p2 y) { return {x.x + y.x, x.y + y.y}; }
p2 operator - (p2 x, p2 y) { return {x.x - y.x, x.y - y.y}; }
p2 operator / (p2 x, db y) { return {x.x / y, x.y / y}; }
p2 operator * (p2 x, db y) { return {x.x * y, x.y * y}; }
p2 operator * (db y, p2 x) { return {x.x * y, x.y * y}; }
db operator * (p2 x, p2 y) { return x.x * y.y - x.y * y.x; }
db operator % (p2 x, p2 y) { return x.x * y.x + x.y * y.y; }
struct line : p2 {
	db z;
	int id;
	// a * x + b * y + c (= or >) 0
	line() = default;
	line(db a, db b, db c) : p2{a, b}, z(c), id(-1) {}
	line(p2 a, p2 b) : p2(r90(b - a)), z(a * b), id(-1) { } //左侧 > 0
	db operator ()(p2 a) const { return a % p2(*this) + z; }
	line perp() const { return {y, -x, 0}; } // 垂直
	line para(p2 o) { return {x, y, z - (*this)(o)}; } // 平行
};
p2 operator & (line x, line y) {
	return p2{p2{x.z, x.y} * p2{y.z, y.y}, p2{x.x, x.z} * p2{y.x, y.z}} / -(p2(x) * p2(y));
	// 注意此处精度误差较大，以及 res.y 需要较高精度
}
p2 proj(p2 x, line l){return x - p2(l) * (l(x) / l.norm());}//投影
p2 refl(p2 x, line l){return x - p2(l) * (l(x) / l.norm()) * 2;}//对称
db dist(line l, p2 x={0, 0}){return l(x) / l.abs();}//有向点到线距离
bool is_para(line x, line y){return eq(p2(x) * p2(y), 0);}//判断线平行
bool is_perp(line x, line y){return eq(p2(x) % p2(y), 0);}//判断线垂直
bool online(p2 x, line l) { return eq(l(x), 0); } // 判断点在线上
int ccw(p2 a, p2 b, p2 c) {
	int sign = sgn((b - a) * (c - a));
	if(sign == 0) {
		if(sgn((b - a) % (c - a)) == -1) return 2;
		if((c - a).norm() > (b - a).norm() + eps) return -2;
	}
	return sign;
}
db det(line a, line b, line c) {
	p2 A = a, B = b, C = c;
	return c.z * (A * B) + a.z * (B * C) + b.z * (C * A);
}
db check(line a, line b, line c) { // sgn same as c(a & b), 0 if error
	return sgn(det(a, b, c)) * sgn(p2(a) * p2(b));
}
bool paraS(line a, line b) { // 射线同向
	return is_para(a, b) && p2(a) % p2(b) > 0;
}
std::vector<line> cut(const std::vector<line> & o, line l) {
	std::vector<line> res;
	int n = size(o);
	for(int i = 0;i < n;++i) {
		line a = o[i], b = o[(i + 1) % n], c = o[(i + 2) % n];
		int va = check(a, b, l), vb = check(b, c, l);
		if(va > 0 || vb > 0 || (va == 0 && vb == 0)) {
			res.push_back(b);
		}
		if(va >= 0 && vb < 0) {
			res.push_back(l);
		}
	}
	if(res.size() <= 2) return {};
	return res;
} // 切凸包
struct seg {
	p2 x, y;
	seg() {}
	seg(const p2 & A, const p2 & B) : x(A), y(B) {}
	bool onseg(const p2 & o) const {
		return (o - x) % (o - y) < eps;
	}
	line to_l() const { return line(x, y); }
};
struct circle : p2 { db r; };
std::vector<p2> operator & (circle o, line l) {
	p2 v = l, Rv = r90(v); db L = l.abs();
	db d = l(p2(o)) / L, x = o.r * o.r - d * d;
	if(x < -eps) return {};
	x = std::sqrt(x * sgn(x));
	p2 z = p2(o) - v * (d / L), p = Rv * (x / L);
	return {z + p, z - p};
} // l 如果是构造函数给出，那么返回交点按射线顺序
std::vector<p2> operator & (circle o, seg s) {
	std::vector<p2> b;
	for(p2 x : (o & s.to_l()))
		if(s.onseg(x)) b.push_back(x);
	return b;
}
std::vector<p2> operator & (circle o0, circle o1) {
	p2 tmp = (p2(o1) - p2(o0)) * 2.;
	return o0 & line(tmp.x, tmp.y, o1.r * o1.r - o0.r * o0.r + o0.norm() - o1.norm());
}
std::vector<p2> tang(circle o, p2 x) {
	db d = (x - p2(o)).abs();
	if(d <= o.r + eps) return {};
	return o & circle{x, sqrt(d * d - o.r * o.r)};
}
// 三角形 (0, a, b) 和圆 o 的交的有向面积 * 2
db intersect(circle o, p2 a, p2 b) {
	a = a - p2(o), b = b - p2(o); o.x = o.y = 0;
	int va = a.abs() <= o.r + eps;
	int vb = b.abs() <= o.r + eps;
	if(va && vb) return a * b;
	auto v = o & seg{a, b}; // 注意这里，有必要改一下 onseg，去掉平行判定
	if(v.empty()) return arg(a, b) * o.r * o.r;
	db sum = 0;
	sum += va ? a * v[0] : arg(a, v[0]) * o.r * o.r;
	sum += vb ? v.back() * b : arg(v.back(), b) * o.r * o.r;
	if(v.size() > 1) sum += v[0] * v[1];
	return sum;
}
line bisector(p2 a, p2 b) { return line(a.x - b.x, a.y - b.y, (b.norm() - a.norm()) / 2); }

int main() {
	int n, k;
	cin >> n >> k;
	std::vector<p2> a(n);
	for(auto & [x, y] : a) {
		cin >> x >> y;
	}
	shuffle(a.begin(), a.end(), std::mt19937_64(12421));
	const db V = 1e5;
	db ans = 0;
	for(int i = 0;i < n;++i) {
		std::vector<line> c = {
				{V, 0, V * V}, {0, V, V * V},
				{-V, 0, V * V}, {0, -V, V * V},
				};
		for(int j = 0;j < n;++j) {
			if(i == j) continue;
			p2 x = a[j];
			line l = bisector(a[i], x);
			l.id = j;
			c = cut(c, l);
		}
		for(int l = 0;l < (int) c.size();++l) {
			if(c[l].id != -1) {
				auto t = c;
				int xid = c[l].id;
				for(int j = 0;j < n;++j) {
					p2 x = a[j];
					if(xid == j || i == j) {
						continue;
					}
					line l = bisector(a[xid], x);
					t = cut(t, l);
				}
				p2 A = a[i], B = a[xid];
				if((A - B).abs() >= k) continue;
				p2 o = (A + B) / 2;
				p2 dx = B - o; dx = dx / dx.abs();
				p2 dy = r90(dx);
				p2 c1 = o + dx * k / 2;
				p2 c2 = o;
				db rr = k;
				for(int c = 50;c >= 0;--c) {
					rr /= 2;
					p2 c22 = c2 + rr * dy;
					if((c22 - A).abs() + (c22 - B).abs() < k) {
						c2 = c22;
					}
				}
				db rate = (c1 - o).abs() / ((c2 - o).abs());
				circle circ = {p2{0, 0}, (c2 - o).abs()};
				auto get = [&](p2 x) {
					x = x - o;
					p2 z;
					z.x = x % dx / rate;
					z.y = x % dy;
					return z;
				};
				std::vector<p2> P(t.size());
				for(int i = 0;i < (int) P.size();++i) {
					P[i] = t[i] & t[(i + 1) % t.size()];
				}
				for(int i = 0;i < (int) P.size();++i) {
					p2 x = P[i], y = P[(i + 1) % t.size()];
					x = get(x);
					y = get(y);
					ans += intersect(circ, x, y) * rate;
				}
			}
		}
	}
	printf("%.20lf\n", ans / 2);
}