#include<bits/stdc++.h>
using std::cin;
using std::cout;
using ll = long long;
using u64 = unsigned long long;
using db = double;
const db eps = 1e-8;
const int N = 2005;

int n, r;
struct func {
	int sgn, x, y;
	db operator () (db p) const {
		return sgn * y + std::sqrt(r * r - (p - x) * (p - x));
	}
	db get(db p) {
		db h = std::sqrt(r * r - p * p);
		return (p * h + r * r * std::atan(p / h)) / 2;
	}
	db inte(db l, db r) {
		return sgn * (r - l) * y + get(r - x) - get(l - x);
	}
};

db lim;
db L, R;
db sgn(db x) {
	return x < -eps ? -1 : x > eps;
}
db integral(db l, db r, std::vector<func> & o) {
	if(o.empty()) return 0;
	db min = 1e18, mid = (l + r) / 2; int id = 0;
	for(int i = 0;i < (int) o.size();++i) {
		db w = o[i](mid);
		if(w < min) {
			min = w;
			id = i;
		}
	}
	if(r - l <= lim) {
		return min * (r - l);
	}
	std::vector<func> L, R;
	db le = l, ri = r;
	func tmp = o[id];
	for(int i = 0;i < (int) o.size();++i) if(i != id) {
		func x = o[i];
		if(x(l) < tmp(l)) L.push_back(x);
		if(x(r) < tmp(r)) R.push_back(x);
		if(x(le) >= tmp(le) && x(ri) >= tmp(ri)) {
			continue;
		}
		if(x(le) < tmp(le)) {
			db l = le, r = mid;
			for(int c = 0;c < 30;++c) {
				db mid = (l + r) / 2;
				if(x(mid) < tmp(mid) - eps) {
					l = mid;
				} else {
					r = mid;
				}
			}
			le = l;
		}
		if(x(ri) < tmp(ri)) {
			db l = mid, r = ri;
			for(int c = 0;c < 30;++c) {
				db mid = (l + r) / 2;
				if(x(mid) < tmp(mid) - eps) {
					r = mid;
				} else {
					l = mid;
				}
			}
			ri = l;
		}
	}
	return tmp.inte(le, ri) + integral(l, le, L) + integral(ri, r, R);
}

int main() {
	std::ios::sync_with_stdio(false), cin.tie(0);
	int T;
	cin >> T;
	for(int i = 0;i < T;++i) {
		cin >> n >> r;
		std::vector<func> a(n);
		L = -1e18, R = 1e18;
		for(func & x : a) {
			cin >> x.x >> x.y;
			x.sgn = 1;
			L = std::max<db>(L, x.x - r);
			R = std::min<db>(R, x.x + r);
		}
		if(n == 1) {
			printf("%.8lf\n", r * r * std::acos(-1));
			continue;
		}
		if(L > R) {
			puts("0");
			continue;
		}
		lim = std::max<db>(R - L, 1) * 1e-6;
		std::vector<func> b = a;
		for(func & x : b) x.sgn = -1;
		db ll = L, rr = R;
		auto eval = [&](db p) {
			db min0 = 1e18;
			db min1 = 1e18;
			for(int i = 0;i < n;++i) {
				min0 = std::min(min0, a[i](p));
				min1 = std::min(min1, b[i](p));
			}
			return min0 + min1;
		};
		for(int i = 0;i < 80;++i) {
			db lm = (ll * 2 + rr) / 3;
			db rm = (ll + rr * 2) / 3;
			if(eval(lm) > eval(rm)) {
				rr = rm;
			} else {
				ll = lm;
			}
		}
		db step = (ll - L);
		for(int i = 0;i < 40;++i) {
			step /= 2;
			if(eval(ll - step) >= 0)
				ll -= step;
		}
		step = R - rr;
		for(int i = 0;i < 40;++i) {
			step /= 2;
			if(eval(rr + step) >= 0)
				rr += step;
		}
		ll += eps;
		rr -= eps;
		db ans = 0;
		if(ll <= rr) {
			static std::mt19937 gen(2);
			shuffle(a.begin(), a.end(), gen);
			shuffle(b.begin(), b.end(), gen);
			ans += integral(ll, rr, a);
			ans += integral(ll, rr, b);
		}
		printf("%.8lf\n", ans);
	}
}