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/*
 *  Copyright (C) 2020  Paweł Widera
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 3 of the License, or
 *  (at your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details:
 *  http://www.gnu.org/licenses/gpl.html
 */
#include <cmath>
#include <iostream>
#include <algorithm>
#include <vector>
using namespace std;


enum class EDir { horizontal, vertical };

struct Point {
	int x;
	int y;
	EDir direction;

	int operator<(const Point& other) const {
		return x + y < other.x + other.y;
	}
};


int main() {
	ios::sync_with_stdio(false);
	cin.tie(nullptr);

	int n, direction, distance, delay;

	vector<Point> cars;

	cin >> n;
	cars.reserve(n);

	for (int i = 0; i < n; ++i) {
		cin >> direction >> distance >> delay;
		if (direction == 1) {
			cars.push_back({distance, -delay, EDir::vertical});
		} else {
			cars.push_back({-delay, distance, EDir::horizontal});
		}
	}

	// sort by left-right diagonals
	stable_sort(cars.begin(), cars.end());

	int removed = 0;
	int v = 0, h = 0;
	int last = cars[0].x + cars[0].y;

	for (auto car: cars) {
		// remove cars causing collisions
		if (car.x + car.y != last) {
			removed += min(v, h);
			v = h = 0;
		}
		// count cars on the same diagonal moving in each direction
		if (car.direction == EDir::vertical) {
			++v;
		} else {
			++h;
		}
		last = car.x + car.y;
	}
	removed += min(v, h);

	cout << removed << endl;
	return 0;
}