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#define _USE_MATH_DEFINES
#include <bits/stdc++.h>
#ifdef LOC
#include "debuglib.h"
#else
#define deb(...)
#define DBP(...)
#endif
using namespace std;
using   ll         = long long;
using   Vi         = vector<int>;
using   Pii        = pair<int, int>;
#define pb           push_back
#define mp           make_pair
#define x            first
#define y            second
#define rep(i, b, e) for (int i = (b); i < (e); i++)
#define each(a, x)   for (auto& a : (x))
#define all(x)       (x).begin(), (x).end()
#define sz(x)        int((x).size())

constexpr int MAX_V = 1e6+100;

int main() {
	cin.sync_with_stdio(0); cin.tie(0);
	cout << fixed << setprecision(10);

	int n; cin >> n;
	vector<pair<int, Pii>> elems(n);
	each(e, elems) cin >> e.x >> e.y.x >> e.y.y;

	sort(all(elems));
	elems.erase(unique(all(elems)), elems.end());

	Vi cnt[2];
	rep(i, 0, 2) cnt[i].resize(MAX_V*2+100);
	each(e, elems) cnt[e.x-1][MAX_V+e.y.x-e.y.y]++;

	int ans = n - sz(elems);
	rep(i, 0, sz(cnt[0])) ans += min(cnt[0][i], cnt[1][i]);
	cout << ans << '\n';
	return 0;
}