#include <cstdio>#include <cstring>#include <algorithm>#include <vector>#define lson rt<<1,l,mid#define rson rt<<1|1,mid + 1,rusing namespace std;const int maxn = 4004;struct Seg {	double l, r, x;	int cover;	Seg(double l, double r, double x, int cover) :l(l), r(r), x(x), cover(cover) {}	//排序大小按照x轴的坐标大小	bool operator < (const Seg &tmp) const {		return x < tmp.x;	}};int n, cnt[maxn << 2];double len[maxn << 2];vector<double> dy;vector<Seg> seg;int GetID(double Val) {	//二分查找点的坐标，离散化	return lower_bound(dy.begin(), dy.end(), Val) - dy.begin();}void pushup(int rt, int l, int r) {	int lc = rt << 1, rc = rt << 1 | 1;	//如果当前线段存在，更新坐标	//这里r+1是因为长度为x的线段有x+1个点，所以最后一个点是r+1	if (cnt[rt]) len[rt] = dy[r + 1] - dy[l];	else if (r == l) len[rt] = 0;		else len[rt] = len[lc] + len[rc];}void update(int rt, int l, int r, int ql, int qr, int Val) {	int lc = rt << 1, rc = rt << 1 | 1, mid = (l + r) >> 1;	if (ql <= l && qr >= r) {		//累加当前线段的值		cnt[rt] += Val;		pushup(rt, l, r);	}	else {		//标记不需要下放，因为当前线段的增减和子线段没有关系		//而且每条线段必定增加一次，减少一次		if (ql <= mid) update(lson, ql, qr, Val);		if (qr > mid) update(rson, ql, qr, Val);		pushup(rt, l, r);	}}int main() {	int kase = 1;	while (scanf("%d", &n),n != 0) {		//初始化线段树		dy.clear(); seg.clear();		memset(cnt, 0, sizeof(cnt));		memset(len, 0, sizeof(len));		//读入数据		for (int i = 1; i <= n; i++) {			double x1, x2, y1, y2; scanf("%lf%lf%lf%lf", &x1, &y1, &x2, &y2);			//将每个矩形抽象成两条线段			seg.push_back(Seg(y1, y2, x1, 1));			seg.push_back(Seg(y1, y2, x2, -1));			//存储每个坐标的值			dy.push_back(y1); dy.push_back(y2);		}		//将浮点坐标离散化		sort(dy.begin(), dy.end());		dy.erase(unique(dy.begin(), dy.end()), dy.end());		//将线段排序		sort(seg.begin(), seg.end());		int msize = seg.size(), k = dy.size();		double ret = 0;		for (int i = 0; i < msize - 1; i++) {			//这里的qr为什么要减一？ 是因为我线段树每个节点存的是l,r之间的线段，而不是点集，把每个线段当成点来看的话，			//每个[l,r]的点构成的线段编号应该是[l,r-1]			int ql = GetID(seg[i].l), qr = GetID(seg[i].r) - 1;			//更新值			update(1, 0, k - 1, ql, qr, seg[i].cover);			//累加当前扫描线扫过的面积			ret += len[1] * (seg[i + 1].x - seg[i].x);		}		printf("Test case #%d\nTotal explored area: %.2lf\n\n", kase++, ret);	}	return 0;}