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#include <iostream>
#include <unordered_map>

int main() {
    std::ios_base::sync_with_stdio(0);
    int n;
    std::cin >> n;
    std::unordered_map<int, int> R[2];
    for (int i=0;i<n;++i) {
        int r,w,t;
        std::cin >> r >> w >> t;
        R[r-1][t-w]++;
    }
    int result = 0;
    for (const auto& x : R[0]) result += std::min(x.second, R[1][x.first]);
    std::cout << result << std::endl;
    return 0;
}