#include <bits/stdc++.h>
using namespace std;

using ld = long double;
const ld eps = 1e-10, pi = acos(-1.0);

bool eq(ld a, ld b) {
	return abs(a - b) < eps;
}

using Point = complex<ld>;
class Line {
public:
	Point a, b;
};
ld dot(Point a, Point b) {
	return real(conj(a) * b);
}

ld cross(Point a, Point b) {
	return imag(conj(a) * b);
}

int ccw(Point a, Point b, Point c) {
	b -= a, c -= a;
	if (cross(b, c) > eps) return 1;	// a,b,c counter-clockwise
	if (cross(b, c) < -eps) return -1;	// a,b,c clockwise
	if (dot(b, c) < 0) return 2;		// c,a,b on a line
	if (norm(b) < norm(c)) return -2;	// a,b,c on a line
	return 0;							// a,c,b on a line
}

bool isis_ll(Line l, Line m) {
	return abs(cross(l.b - l.a, m.b - m.a)) > eps;
}

bool isis_ls(Line l, Line s) {
	return (cross(l.b - l.a, s.a - l.a) * cross(l.b - l.a, s.b - l.a) < eps);
}

bool isis_lp(Line l, Point p) {
	return abs(cross(l.b - p, l.a - p)) < eps;
}

bool isis_sp(Line s, Point p) {
	return abs(s.a - p) + abs(s.b - p) - abs(s.b - s.a) < eps;
}

Point proj(Line l, Point p) {
	ld t = dot(p - l.a, l.a - l.b) / norm(l.a - l.b);
	return l.a + t * (l.a - l.b);
}

Point is_ll(Line s, Line t) {
	Point sv = s.b - s.a, tv = t.b - t.a;
	assert(cross(sv, tv) != 0);
	return s.a + sv * cross(tv, t.a - s.a) / cross(tv, sv);
}

bool isis_ss(Line s, Line t) {
	if (isis_ll(s, t)) return isis_ls(s, t) && isis_ls(t, s);
	return isis_sp(s, t.a) || isis_sp(s, t.b) || isis_sp(t, s.a);
}

ld dist_lp(Line l, Point p) {
	return abs(p - proj(l, p));
}

ld dist_ll(Line l, Line m) {
	return isis_ll(l, m) ? 0 : dist_lp(l, m.a);
}

ld dist_ls(Line l, Line s) {
	return isis_ls(l, s) ? 0 : min(dist_lp(l, s.a), dist_lp(l, s.b));
}

ld dist_sp(Line s, Point p) {
	Point r = proj(s, p);
	return isis_sp(s, r) ? abs(r - p) : min(abs(s.a - p), abs(s.b - p));
}

ld dist_ss(Line s, Line t) {
	if (isis_ss(s, t)) return 0;
	return min({ dist_sp(s, t.a), dist_sp(s, t.b), dist_sp(t, s.a), dist_sp(t, s.b) });
}

bool is_in_polygon(const vector<Point>& poly, const Point& p) {
	int n = poly.size();
	ld sum = 0;
	for (int i = 0; i < n; ++i) {
		Point p1 = poly[i], p2 = poly[(i + 1) % n];
		if (isis_sp((Line) { p1, p2 }, p)) return true;
		sum += arg((p2 - p) / (p1 - p));
	}
	return abs(sum) > pi;
}

ld calc(const Line& l, const vector<Point>& ps) {
	int n = ps.size();
	Point v = l.b - l.a;
	assert(abs(v) > eps);
	v /= abs(v);
	vector<ld> pos = { 0, abs(l.b - l.a) };
	for (int i = 0; i < n; i++) {
		Line s = { ps[i], ps[(i + 1) % n] };
		if (abs(cross(l.b - l.a, s.b - s.a)) > eps && isis_ss(l, s)) {
			auto pp = is_ll(l, s);
			ld x = dot(pp - l.a, v);
			if (0 < x && x < pos[1]) pos.push_back(x);
		}
	}
	sort(pos.begin(), pos.end());
	ld res = 0;
	for (int i = 1; i < (int)pos.size(); i++) {
		if (!is_in_polygon(ps, l.a + v * ((pos[i] + pos[i - 1]) / 2.0))) break;
		res = pos[i];
	}
	return res;
}

int main()
{
	ios::sync_with_stdio(false), cin.tie(0);
	cout << fixed << setprecision(10);
	int n, tcase = 0;
	while (cin >> n, n) {
		vector<Point> ps;
		for (int i = 0; i < n; i++) {
			ld x, y;
			cin >> x >> y;
			ps.emplace_back(x, y);
		}
		ld res = 0;
		for (int i = 0; i < n; i++) {
			for (int j = i + 1; j < n; j++) {
				Line l = { ps[i], ps[j] };
				if (calc(l, ps) < abs(l.a - l.b) - eps) continue;
				Point v = ps[j] - ps[i];
				assert(abs(v) > eps);
				v /= abs(v);
				Point p1 = ps[j] + v * calc((Line) { ps[j], ps[j] + v * (ld)1e5 }, ps);
				Point p2 = ps[i] - v * calc((Line) { ps[i], ps[i] - v * (ld)1e5 }, ps);
				res = max(res, abs(p1 - p2));
			}
		}
		cout << "Case " << ++tcase << ": " << res << endl;
	}
	return 0;
}



Measured memory_bytes: 3324