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#include <iostream>
#include <set>
#include <vector>
#include <utility>
#include <map>
#include <queue>
#include <algorithm>
#include <string>
#include <map>
using namespace std;
#define PB push_back
#define MP make_pair
#define F first
#define S second
typedef long long ll;
typedef pair<int, int> pii;
const int INF = 1e9;

int n;

vector<map<int, int>> mymaps;

void solve() {
    cin >> n;
    mymaps.resize(2);
    int r, w, t;
    for (int i = 0; i < n; i++) {
        cin >> r >> w >> t;
        mymaps[r - 1][w - t]++;
    }

    int res = 0;
    for (pii p : mymaps[0]) {
        res += min(p.S, mymaps[1][p.F]);
    }

    cout << res << endl;

}

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

    solve();

    return 0;
}