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#include <ctime>
#include <cassert>
#include <iostream>
#include <iomanip>
#include <vector>
#include <algorithm>
#include <unordered_map>
using namespace std;
const int MAXN = 500000;

#define FOR(i, n) for(int i = 0, __n = (n); i < __n; i++)


int main() {
  ios_base::sync_with_stdio(0);
  int n;
  cin >> n;
  unordered_map<int,int> P[2];

  FOR(i, n) {
    int r, w, t;
    cin >> r >> w >> t;
    P[r-1][t-w]++;
  }

  int total = 0;
  for (auto v : P[0]) {
    total += min(v.second, P[1][v.first]);
  }
  cout << total << endl;
}