import java.io.*;
import java.util.*;

public class Main {
    public static void main(String[] args) throws Exception {
        Scanner sc = new Scanner();
        int n = sc.nextInt();
        ArrayList<ArrayList<Box>> boxes = new ArrayList<>();
        boxes.add(new ArrayList<>());
        boxes.get(0).add(new Box(Integer.MAX_VALUE, Integer.MAX_VALUE, Integer.MAX_VALUE));
        Box[] tmp = new Box[n];
        for (int i = 0; i < n; i++) {
            tmp[i] = new Box(sc.nextInt(), sc.nextInt(), sc.nextInt());
        }
        Arrays.sort(tmp);
        for (Box b : tmp) {
            for (int j = boxes.size() - 1; j >= 0; j--) {
                boolean ng = true;
                for (Box x : boxes.get(j)) {
                    if (x.isSmaller(b)) {
                        ng = false;
                        break;
                    }
                }
                if (!ng) {
                    if (j == boxes.size() - 1) {
                        boxes.add(new ArrayList<>());
                    }
                    boxes.get(j + 1).add(b);
                    break;
                }
            }
        }
        System.out.println(boxes.size() - 1);
    }
    
    static class Box implements Comparable<Box> {
        int big;
        int middle;
        int small;
        
        public Box(int[] arr) {
            Arrays.sort(arr);
            small = arr[0];
            middle = arr[1];
            big = arr[2];
        }
        
        public Box(int a, int b, int c) {
            this(new int[]{a, b, c});
        }
        
        public int compareTo(Box another) {
            if (big == another.big) {
                if (middle == another.middle) {
                    return another.small - small;
                } else {
                    return another.middle - middle;
                }
            } else {
                return another.big - big;
            }
        }
        
        public boolean isSmaller(Box another) {
            return big > another.big && middle > another.middle && small > another.small;
        }
    }
}
class Scanner {
    BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
    StringTokenizer st = new StringTokenizer("");
    
    public Scanner() throws Exception {
        
    }
    
    public int nextInt() throws Exception {
        return Integer.parseInt(next());
    }
    
    public long nextLong() throws Exception {
        return Long.parseLong(next());
    }
    
    public double nextDouble() throws Exception {
        return Double.parseDouble(next());
    }
    
    public String next() throws Exception {
        if (!st.hasMoreTokens()) {
            st = new StringTokenizer(br.readLine());
        }
        return st.nextToken();
    }
}