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/*
 * author: pavveu
 * task: Potyczki Algorytmiczne 2020 Runda 3 - Samochody Dostawcze [C] 
*/

#include <bits/stdc++.h>

using namespace std;

using ll = long long;
using vi = vector<int>;
using vll = vector<ll>;

#define FOR(iter, val) for(int iter = 0; iter < (val); iter++)
#define all(x) begin(x), end(x)

struct point {
	int type, x, y;
	point(int tt = 0, int xx=0, int yy=0) : type{tt}, x{xx}, y{yy} {}
};


void go() {
	int n; cin >> n;
	vector<point> points(n);
	unordered_map<int,int> cnt[2];

	vector<int> diffs;

	for (auto& p : points) {
		cin >> p.type >> p.x >> p.y;
		p.type--;
		p.y = -p.y;

		if ( p.type == 1 ) swap(p.x, p.y);

		cnt[p.type][p.x + p.y]++;
		diffs.push_back(p.x + p.y);
	}

	sort(all(diffs));
	auto end_it = unique(all(diffs));
	diffs.erase(end_it, diffs.end());

	int ans { 0 };
	for (int sum_coords : diffs) {
		ans += std::min(cnt[0][sum_coords], cnt[1][sum_coords]);
	}

	cout << ans << endl;
}

int main() {
	ios::sync_with_stdio(false);
	cin.tie(0);

	go();
	// test();

	return 0;
}