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


public class Main_yukicoder497 {

	private static Scanner sc;
	private static Printer pr;

	private static void solve() {
		int n = sc.nextInt();

		int[] x = new int[n];
		int[] y = new int[n];
		int[] z = new int[n];
		for (int i = 0; i < n; i++) {
			x[i] = sc.nextInt();
			y[i] = sc.nextInt();
			z[i] = sc.nextInt();
		}

		List<List<Edge>> edges = new ArrayList<>(n + 2);
		for (int i = 0; i < n + 2; i++) {
			edges.add(new ArrayList<>());
		}

		int sp = n;
		int ep = n + 1;
		for (int i = 0; i < n; i++) {
			edges.get(sp).add(new Edge(sp, i, 1));
			edges.get(i).add(new Edge(i, ep, 0));

			for (int j = i + 1; j < n; j++) {
				if ((x[i] < x[j] && y[i] < y[j] && z[i] < z[j])
						|| (x[i] < y[j] && y[i] < x[j] && z[i] < z[j])
						|| (x[i] < z[j] && y[i] < y[j] && z[i] < x[j])
						|| (x[i] < x[j] && y[i] < z[j] && z[i] < y[j])

						|| (x[i] < y[j] && y[i] < z[j] && z[i] < x[j])
						|| (x[i] < z[j] && y[i] < x[j] && z[i] < y[j])
						) {
					edges.get(i).add(new Edge(i, j, 1));
				} else if ((x[i] > x[j] && y[i] > y[j] && z[i] > z[j])
						|| (x[i] > y[j] && y[i] > x[j] && z[i] > z[j])
						|| (x[i] > z[j] && y[i] > y[j] && z[i] > x[j])
						|| (x[i] > x[j] && y[i] > z[j] && z[i] > y[j])

						|| (x[i] > y[j] && y[i] > z[j] && z[i] > x[j])
						|| (x[i] > z[j] && y[i] > x[j] && z[i] > y[j])
						) {
					edges.get(j).add(new Edge(j, i, 1));
				}
			}
		}

		n += 2;
		boolean[] used = new boolean[n];
		boolean[] gray = new boolean[n];

		List<Integer> ts = new ArrayList<>();
		for (int i = 0; i < n; i++) {
			Deque<Integer> st = new ArrayDeque<>();
			st.push(i);
			while (!st.isEmpty()) {
				int e = st.peek();

				if (used[e]) {
					st.pop();
					continue;
				}

				if (gray[e]) {
					st.pop();
					used[e] = true;
					ts.add(e);
				} else {
					gray[e] = true;
					for (Edge next : edges.get(e)) {
						if (used[next.v]) {
							continue;
						}
						if (gray[next.v]) {
							// 後退辺
							continue;
						}

						st.push(next.v);
					}
				}
			}
		}

		Collections.reverse(ts);
		int[] d = new int[n + 2];
		for (int e : ts) {
			for (Edge next : edges.get(e)) {
				d[next.v] = Math.max(d[next.v], d[e] + next.w);
			}
		}

		pr.println(d[ep]);
	}

	private static class Edge {
		@SuppressWarnings("unused")
		int u; // from
		int v; // to
		int w; // cost

		Edge(int u, int v, int w) {
			this.u = u;
			this.v = v;
			this.w = w;
		}
	}

	// ---------------------------------------------------
	public static void main(String[] args) {
		sc = new Scanner(System.in);
		pr = new Printer(System.out);

		solve();

		pr.close();
		sc.close();
	}

	@SuppressWarnings("unused")
	private static class Scanner {
		BufferedReader br;

		Scanner (InputStream in) {
			br = new BufferedReader(new InputStreamReader(in));
		}

		private boolean isPrintable(int ch) {
			return ch >= '!' && ch <= '~';
		}

		private boolean isCRLF(int ch) {
			return ch == '\n' || ch == '\r' || ch == -1;
		}

		private int nextPrintable() {
			try {
				int ch;
				while (!isPrintable(ch = br.read())) {
					if (ch == -1) {
						throw new NoSuchElementException();
					}
				}

				return ch;
			} catch (IOException e) {
				throw new NoSuchElementException();
			}
		}

		String next() {
			try {
				int ch = nextPrintable();
				StringBuilder sb = new StringBuilder();
				do {
					sb.appendCodePoint(ch);
				} while (isPrintable(ch = br.read()));

				return sb.toString();
			} catch (IOException e) {
				throw new NoSuchElementException();
			}
		}

		int nextInt() {
			try {
				// parseInt from Integer.parseInt()
				boolean negative = false;
				int res = 0;
				int limit = -Integer.MAX_VALUE;
				int radix = 10;

				int fc = nextPrintable();
				if (fc < '0') {
					if (fc == '-') {
						negative = true;
						limit = Integer.MIN_VALUE;
					} else if (fc != '+') {
						throw new NumberFormatException();
					}
					fc = br.read();
				}
				int multmin = limit / radix;

				int ch = fc;
				do {
					int digit = ch - '0';
					if (digit < 0 || digit >= radix) {
						throw new NumberFormatException();
					}
					if (res < multmin) {
						throw new NumberFormatException();
					}
					res *= radix;
					if (res < limit + digit) {
						throw new NumberFormatException();
					}
					res -= digit;

				} while (isPrintable(ch = br.read()));

				return negative ? res : -res;
			} catch (IOException e) {
				throw new NoSuchElementException();
			}
		}

		long nextLong() {
			try {
				// parseLong from Long.parseLong()
				boolean negative = false;
				long res = 0;
				long limit = -Long.MAX_VALUE;
				int radix = 10;

				int fc = nextPrintable();
				if (fc < '0') {
					if (fc == '-') {
						negative = true;
						limit = Long.MIN_VALUE;
					} else if (fc != '+') {
						throw new NumberFormatException();
					}
					fc = br.read();
				}
				long multmin = limit / radix;

				int ch = fc;
				do {
					int digit = ch - '0';
					if (digit < 0 || digit >= radix) {
						throw new NumberFormatException();
					}
					if (res < multmin) {
						throw new NumberFormatException();
					}
					res *= radix;
					if (res < limit + digit) {
						throw new NumberFormatException();
					}
					res -= digit;

				} while (isPrintable(ch = br.read()));

				return negative ? res : -res;
			} catch (IOException e) {
				throw new NoSuchElementException();
			}
		}

		float nextFloat() {
			return Float.parseFloat(next());
		}

		double nextDouble() {
			return Double.parseDouble(next());
		}

		String nextLine() {
			try {
				int ch;
				while (isCRLF(ch = br.read())) {
					if (ch == -1) {
						throw new NoSuchElementException();
					}
				}
				StringBuilder sb = new StringBuilder();
				do {
					sb.appendCodePoint(ch);
				} while (!isCRLF(ch = br.read()));

				return sb.toString();
			} catch (IOException e) {
				throw new NoSuchElementException();
			}
		}

		void close() {
			try {
				br.close();
			} catch (IOException e) {
//				throw new NoSuchElementException();
			}
		}
	}

	private static class Printer extends PrintWriter {
		Printer(PrintStream out) {
			super(out);
		}
	}
}