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#if defined(EMBE_DEBUG) && !defined(NDEBUG)
#include "embe-debug.hpp"
#else
#define LOG_INDENT(...) do {} while (false)
#define LOG(...) do {} while (false)
#define DUMP(...) do {} while (false)
#endif

#include <map>
#include <iostream>
using namespace std;

int main()
{
  iostream::sync_with_stdio(false);
  cin.tie(nullptr);

  int n;
  cin >> n;

  map<int, array<int, 2>> count;
  for (int i = 0; i < n; ++i) {
    int r, w, t;
    cin >> r >> w >> t;
    ++count[w - t][r - 1];
  }

  int res = 0;
  for (auto const& [t, c]: count) {
    res += min(c[0], c[1]);
  }

  cout << res << endl;

  return 0;
}