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#include <iostream>
#include <cstdio>
#include <cstdlib>
#include <algorithm>
#include <set>
#include <map>
#include <utility>
#include <queue>
#include <vector>
#include <string>
#include <cstring>

#define REP(a,n) for (int a = 0; a<(n); ++a)
#define FOR(a,b,c) for (int a = (b); a<=(c); ++a)
#define FORD(a,b,c) for (int a = (b); a>=(c); --a)
#define FOREACH(a,v) for (auto a : v)

#define MP make_pair
#define PB push_back

template<class T> inline int size(const T&t) { return t.size(); }

using namespace std;

typedef pair<int, int> pii;
typedef vector<int> vi;
typedef vector<string> vs;
typedef long long LL;

///////////////////////////////

int N;
pii tab[500000];

int main() {
  cin >> N;
  REP(a, N) {
    int x, y, z;
    cin >> x >> y >> z;
    tab[a] = MP(y - z, x);
  }
  sort(tab, tab + N);
  int p = 0;
  int res = 0;
  while (p < N) {
    int p2 = p;
    while (p2 < N && tab[p2] == tab[p])
      ++p2;
    int p3 = p2;
    while (p3 < N && tab[p3].first == tab[p].first)
      ++p3;
    res += min(p3 - p2, p2 - p);
    p = p3;
  }
  cout << res << endl;
}