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#pragma GCC optimize("O3")
#pragma GCC optimize("unroll-loops")

#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>

using namespace std;
using namespace __gnu_pbds;

typedef uint32_t ul;
typedef int32_t l;
typedef uint64_t ull;
typedef int64_t ll;

template <typename T>
using statistics_set = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;

const l INF = 1000000000 + 9;
const ll MOD = 123456789;
const l PRIME = 200003;
const ll L_INF = 1000000000000000000LL + 7;
const double EPS = 1e-5;

#define FOR(x, y, z) for (l z = x; z < y; z++)
#define FORE(x, y, z) for (l z = x; z <= y; z++)
#define FORD(x, y, z) for (l z = x; z > y; z--)
#define FORDE(x, y, z) for (l z = x; z >= y; z--)
#define REP(x, y) for (l y = 0; y < x; y++)
#define ALL(...) (__VA_ARGS__).begin(), (__VA_ARGS__).end()

#define PF push_front
#define POF pop_front
#define PB push_back
#define POB pop_back
#define MP make_pair
#define FS first
#define SC second

const l MAXN = 1000005;

l n, res;
map<l, l> M[2];

int main()
{
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr); cout.tie(nullptr);

    cin >> n;

    FORE(1, n, i)
    {
        l a, b, c;
        cin >> a >> b >> c;
        a--;

        M[a][b-c]++;
    }

    for(auto u: M[0])
        if(M[1].find(u.FS) != M[1].end())
            res += min(u.SC, M[1][u.FS]);

    cout << res << "\n";
}