#include <cstdio>
#include <cstdlib>

#include <map>

int main() {
    int n;
    scanf("%d", &n);

    struct trucks {
        int count[2] = { 0, 0 };
    };

    std::map<int, trucks> counts;

    while (n --> 0) {
        int typ, coord, tim;
        scanf("%d %d %d", &typ, &coord, &tim);
        counts[coord - tim].count[typ-1]++;
    }

    int recall_count = 0;
    for (const auto& p : counts) {
        recall_count += std::min(p.second.count[0], p.second.count[1]);
    }

    printf("%d\n", recall_count);
    return 0;
}