#include <iostream>
#include <vector>
#include <algorithm>
#include <cmath>
#include <queue>
#include <string>
#include <map>
#include <set>
#include <stack>
#include <tuple>
#include <deque>
#include <array>
#include <numeric>
#include <bitset>
#include <iomanip>
#include <cassert>
#include <chrono>
#include <random>
#include <limits>
#include <iterator>
#include <functional>
#include <sstream>
#include <fstream>
#include <complex>
#include <cstring>
#include <unordered_map>
#include <unordered_set>
using namespace std;

using ll = long long;
constexpr int INF = 1001001001;
constexpr int mod = 1000000007;
// constexpr int mod = 998244353;

template<class T>
inline bool chmax(T& x, T y){
    if(x < y){
        x = y;
        return true;
    }
    return false;
}
template<class T>
inline bool chmin(T& x, T y){
    if(x > y){
        x = y;
        return true;
    }
    return false;
}

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

    int N;
    cin >> N;
    vector<vector<int>> X(N, vector<int>(3));
    for(int i = 0; i < N; ++i){
        for(int j = 0; j < 3; ++j){
            cin >> X[i][j];
        }
    }

    vector<vector<int>> g(N);
    vector<int> indeg(N);
    for(int i = 0; i < N; ++i){
        for(int j = 0; j < N; ++j){
            if(j != i){
                bool directed = false;
                for(int k = 0; k < 3; ++k){
                    if(X[i][0] < X[j][k]){
                        int pk = (k - 1 + 3) % 3, nk = (k + 1) % 3;
                        if((X[i][1] < X[j][pk] && X[i][2] < X[j][nk]) || (X[i][1] < X[j][nk] && X[i][2] < X[j][pk])){
                            directed = true;
                        }
                    }
                }
                if(directed){
                    g[i].emplace_back(j);
                    indeg[j] += 1;
                }
            }
        }
    }

    vector<int> dp(N, 1);
    queue<int> que;
    for(int i = 0; i < N; ++i){
        if(indeg[i] == 0)   que.emplace(i);
    }
    while(!que.empty()){
        int from = que.front();
        que.pop();
        for(int to : g[from]){
            chmax(dp[to], dp[from] + 1);
            if(--indeg[to] == 0)    que.emplace(to);
        }
    }

    cout << *max_element(begin(dp), end(dp)) << endl;

    return 0;
}