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#include <iostream>
#include <vector>
#include <map>
#include <unordered_map>
#include <unordered_set>

using namespace std;

map<int, pair<int, int>> collisions;

void readDeliveries(int size,
					vector<pair<int, int>>& vertical,
					vector<pair<int, int>>& horizontal) {

	int type, loc, time;
	for (int i = 0; i < size; ++i) {
		cin >> type;
		cin >> loc;
		cin >> time;

		int key = time - loc;
		if (collisions.find(key) == collisions.end()) {
			collisions[key] = pair<int, int>(0,0);
		}

		if (type % 2 == 1) {
			collisions[key].first += 1;
		} else {
			collisions[key].second += 1;
		}
	}
}

int removeCollisions() {
	int deleted = 0;

	while (collisions.size() != 0) {
		pair<int, int> collision = (*collisions.begin()).second;
		if (collision.first == 0 || collision.second == 0) {
			//they won't even collide
			collisions.erase(collisions.begin());
		} else {
			deleted += min(collision.first, collision.second);
			collisions.erase(collisions.begin());				
		}
	}

	return deleted;
};

int main() {
	int size;
	cin >> size;
	vector<pair<int, int>> vertical;
	vector<pair<int, int>> horizontal;

	readDeliveries(size, vertical, horizontal);
	cout << removeCollisions() << endl;

	return 0;
}