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#include<cstdio>
#include<vector>
#include<algorithm>

using namespace std;

vector<pair<int, int>> V;
vector<pair<int, int>> W;

int main() {
    int n;
    scanf("%i", &n);
    for (int i = 0; i < n; ++i) {
        int r, w, t;
        scanf("%i%i%i", &r, &w, &t);
        t -= w;
        
        V.push_back(make_pair(t, r));
    }
    
    sort(V.begin(), V.end());
    
    
    
    int prevT = V[0].first;
    int prevR = V[0].second;
    int cnt = 0;
    for (int i = 0; i < V.size(); ++i) {
        if (V[i].first == prevT and V[i].second == prevR) {
            cnt++;
        } else {
            W.push_back(make_pair(prevT, cnt));
            cnt = 1;
            prevT = V[i].first;
            prevR = V[i].second;
        }
    }
    W.push_back(make_pair(prevT, cnt));
    
    int res = 0;
    for (int i = 1; i < W.size(); ++i) {
        if (W[i-1].first == W[i].first) {
            res += min(W[i-1].second, W[i].second);
        }
    }
    
    printf("%i\n", res);
    
    return 0;
}