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#include <bits/stdc++.h>
using namespace std;

unordered_map<int,int> M[2];
unordered_set<int> coords;

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

  int n;
  cin >> n;
  for (int i = 0; i < n; i++) {
    int type, x, y;
    cin >> type >> x >> y;
    M[type-1][x-y]++;
    coords.insert(x-y);
  }

  int result = 0;
  for (int x : coords) result += min(M[0][x], M[1][x]);
  cout << result << "\n";

  return 0;
}