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#include <bits/stdc++.h>
using namespace std;
#define fi first
#define se second
#define pb push_back
typedef pair <int, int> pii;
typedef long long ll;
typedef double db;

const int N = 1e6;

int n, a, b, c, res;
int tab[N + N + 5][2];

int main()
{
	ios_base::sync_with_stdio(false);
	cin.tie(NULL);
	cout.tie(NULL);	
	
	cin >> n;
	for(int i=1; i<=n; i++){
		cin >> a >> b >> c;
		tab[b - c + N][a % 2] ++;	
	}
	for(int i=1; i<=N+N; i++){
		res += min(tab[i][0], tab[i][1]);
	}
	cout << res << "\n";
	
	return 0;
}