#include <cstdio>#include <cstring>#include <algorithm>#include <vector>#include <iostream>#include <cmath>#include <cassert>#include <map>#define REP(i, n) for (int i = 0; i < n; ++i) using namespace std;#define MP make_pair#define PB push_backstruct pt { int x, y; pt() {} pt(int _x, int _y) : x(_x), y(_y) {} void read() { scanf("%d%d",&x, &y); } pt operator + (const pt& a) const { return pt(x+a.x, y+a.y); } pt operator - (const pt& a) const { return pt(x-a.x, y-a.y); } pt operator * (const int a) const { return pt(x*a, y*a); } int len() const { return sqrt(x*x + y*y); } pt trunc(int s) const { int l = len(); return pt(x*s/l, y*s/l); } void write() { printf("(%d %d) ",x, y); }; bool operator < (const pt& a) const { return x < a.x || (x == a.x && y < a.y); }};int det(const pt& a, const pt& b) { return a.x*b.y - a.y*b.x; }int dot(const pt& a, const pt& b) { return a.x*b.x + a.y*b.y; }void Assert(int x) { if (!x) while (1) puts("***");}bool intersect(int a, int b, int c, int d) { return max(a, c) <= min(b, d);}bool cross(pt a, pt b, pt c, pt d) { if (a.x == b.x) return c.y <= b.y && c.y >= a.y; else return c.x <= b.x && c.x >= a.x;}pt cross_point(pt a,pt b,pt c,pt d) { if (a.x == b.x) return pt(a.x, c.y); else return pt(c.x, a.y);}const int V = 11000;pair<pt, pt> seg[1000];struct Graph { int low[V], now[V], dfn[V]; int loop_num; int n, bnum, sign, top; bool ge[V]; vector<int> adj[V]; vector<int> block[V*2]; pair<int,int> stack[100000]; void connect(int a,int b) { adj[a].push_back(b); adj[b].push_back(a); } void dfs(int v,int fa) { dfn[v] = low[v] = ++sign; int son = 0; ge[v] = false; for (int i=0;i<adj[v].size();i++) if (adj[v][i] != fa) { int u = adj[v][i]; if (dfn[u] == 0) { stack[++top] = make_pair(v,u); dfs(u, v); low[v] = min(low[v], low[u]); if (low[u] >= dfn[v]) { block[++bnum].clear(); do { int l = stack[top].first; int r = stack[top].second; if (now[l] != bnum) { block[bnum].push_back(l); now[l] = bnum; } if (now[r] != bnum) { block[bnum].push_back(r); now[r] = bnum; } top--; }while (!(stack[top+1].first == v && stack[top+1].second == u)); if (v != 1) ge[v] = true; } if (v == 1) if (++son > 1) ge[v] = true; } else low[v] = min(low[v], dfn[u]); } } int SccNum() { memset(dfn, 0, sizeof(dfn)); memset(ge, 0, sizeof(ge)); memset(now, 0, sizeof(now)); sign = top = 0; bnum = 0; for (int i = 0; i < n;++i) if (dfn[i] == 0) dfs(i, -1); int ret = 0; for (int i = 1; i <= bnum; ++i) { if (block[i].size() > 2) ret++; } return ret; } void init() { REP(i, V) adj[i].clear(); }};Graph graph;int n;void fix(pt& a, pt& b) { if (a.x == b.x) { if (a.y > b.y) swap(a, b); } else { if (a.x > b.x) swap(a, b); }}void MergeSeg(map<int, vector<pair<int,int> > >& mp, int x_or_y, int& cnt) { map<int, vector<pair<int,int> > >::iterator it; for (it = mp.begin(); it != mp.end(); ++it) { vector<pair<int,int> >& vec = it->second; int x = it->first, y = it->first; sort(vec.begin(), vec.end()); int lmost, rmost; for (int i = 0; i < vec.size(); ++i) { if (i == 0) { lmost = vec[0].first; rmost = vec[0].second; continue; } if (vec[i].first > rmost) { if (x_or_y == 0) seg[cnt++] = MP(pt(x, lmost), pt(x, rmost)); else seg[cnt++] = MP(pt(lmost, y), pt(rmost, y)); lmost = vec[i].first; } rmost = max(rmost, vec[i].second); } if (rmost > lmost) { if (x_or_y == 0) seg[cnt++] = MP(pt(x, lmost), pt(x, rmost)); else seg[cnt++] = MP(pt(lmost, y), pt(rmost, y)); } }}int MergeSeg() { map<int, vector<pair<int,int> > > mp_x, mp_y; for (int i = 0; i < n; ++i) { if (seg[i].first.x == seg[i].second.x) mp_x[seg[i].first.x].PB(MP(seg[i].first.y, seg[i].second.y)); else if (seg[i].first.y == seg[i].second.y) mp_y[seg[i].first.y].PB(MP(seg[i].first.x, seg[i].second.x)); } int cnt = 0; MergeSeg(mp_x, 0, cnt); MergeSeg(mp_y, 1, cnt); return cnt;}int main() { while (~scanf("%d",&n) && n != 0) { REP(i, n) { seg[i].first.read(); seg[i].second.read(); fix(seg[i].first, seg[i].second); } n = MergeSeg(); map<pt, int> index; graph.init(); int cnt = 0; for (int i = 0; i < n; ++i) { vector<pt> tmp; for (int j = 0; j < n; ++j) { if (i != j) { if (cross(seg[i].first, seg[i].second, seg[j].first, seg[j].second)) { pt c = cross_point(seg[i].first, seg[i].second, seg[j].first, seg[j].second); if (index.find(c) == index.end()) index[c] = cnt++; tmp.push_back(c); } } } sort(tmp.begin(), tmp.end()); for (int j = 0; j < (int)tmp.size()-1; ++j) { graph.connect(index[tmp[j]], index[tmp[j+1]]); } } graph.n = cnt; Assert(cnt < 10000); cout << graph.SccNum() << endl; }}
