south-2011:C. Doesn't work.

C.cpp

#include <iostream>
#include <cstdlib>
#include <vector>
#include <algorithm>
#include <cstdio>

using namespace std;

struct Line{
	int x1, y1, x2, y2;
	bool operator<(const Line &l){
		return x1 == x2 ? y1 < l.y1 : x1 < l.x1;
	}
	Line(istream& is){
		is >> x1 >> y1 >> x2 >> y2;
		if(x1 > x2) swap(x1, x2);
		if(y1 > y2) swap(y1, y2);
	}
};

struct Pt{
	int h, v, x, y;
	int hpos, vpos;
	Pt(int h, int v, int hp, int vp, int x, int y):h(h), v(v),hpos(hp), vpos(vp), x(x), y(y){}
	friend ostream& operator<<(ostream &os, Pt &p){
		return os << p.x << ":" << p.y << " ";
	}
};

int main(){
#ifndef ONLINE_JUDGE
	freopen("in.txt", "r", stdin);
#endif
	int n;
	cin >> n;
	vector<Line> h, v;
	for(int i = 0; i < n; i++){
		Line l(cin);
		(l.y1 == l.y2 ? h : v).push_back(l);
	}
	sort(h.begin(), h.end());
	sort(v.begin(), v.end());

	vector<vector<Pt> > hp(h.size()), vp(v.size());
	for(int i = 0; i < h.size(); i++){
		for(int j = 0; j < v.size(); j++){
			Line &hl = h[i], &vl = v[j];
			if(hl.x1 <= vl.x1 && hl.x2 >= vl.x2 && vl.y1 <= hl.y1 && vl.y2 >= hl.y2){
				Pt p(i, j, hp[i].size(), vp[j].size(), vl.x1, hl.y1);
				hp[i].push_back(p);
				vp[j].push_back(p);
			}
		}
	}
	int cnt = 0;
	for(int i = 0; i < hp.size(); i++){
		vector<Pt> &hh = hp[i];
		for(int j = 0; j < hh.size(); j++){
			Pt &p = hh[j];
			for(int k = p.hpos + 1; k < hh.size(); k++){
				Pt &ph1 = hh[k];
				vector<Pt> &vv = vp[ph1.v];
				for(int l = ph1.vpos + 1; l < vv.size(); l++){
					Pt &pv1 = vv[l];
					vector<Pt> &hh2 = hp[pv1.h];
					for(int m = 0; m < pv1.hpos; m++){
						Pt &ph2 = hh[m];
						if(ph2.v == p.v){
							cnt++;
							//cout << p << ph1 << pv1 << ph2 << endl;
							break;
						}
					}
				}
			}
		}
	}
	cout << cnt;
	return 0;
}

Im fool. solution is http://codeforces.ru/blog/entry/2923#comment-59324