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#include <bits/stdc++.h>
#define qio ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0)
#define debug(x) cerr<<#x<<" "<<x<<endl
#define ll long long 
#define st first
#define nd second
using namespace std;

int n, t, r, w, wys[4][4000006], res;
int main()
{
	qio;
	cin >> n;

	for (int i = 1; i <= n; i++) {
		cin >> r >> w >> t;
		wys[r][w - t + 2000000]++;
	}

	for (int j = 0; j <= 4000000; j++) {
		res += min(wys[1][j], wys[2][j]);
	}

	cout << res << endl;

}