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(); } BellmanFord bf = new BellmanFord(n + 2); int s = n; int e = n + 1; for (int i = 0; i < n; i++) { bf.addEdge(s, i, 0); bf.addEdge(i, e, 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]) ) { bf.addEdge(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]) ) { bf.addEdge(j, i, -1); } } } long tmp = bf.getShortestPath(s, e); if (tmp == 0) { pr.println(1); } else { pr.println(-tmp + 1); } } private static class BellmanFord { long[] d; List edges; int n; int s; final long INF = Long.MAX_VALUE; BellmanFord(int n) { this.n = n; edges = new ArrayList(); s = -1; } // i, j:0-indexed public void addEdge(int i, int j, int c) { edges.add(new Edge(i, j, c)); } // 負閉路があれば -INF を返す public long getShortestPath(int i, int j) { if (s != i) { d = new long[n]; Arrays.fill(d, INF); d[i] = 0; boolean update = false; for (int kk = 0; kk < n - 1; kk++) { update = false; for (int jj = 0; jj < edges.size(); jj++) { if (d[edges.get(jj).u] != INF && d[edges.get(jj).v] > d[edges.get(jj).u] + edges.get(jj).w) { d[edges.get(jj).v] = d[edges.get(jj).u] + edges.get(jj).w; update = true; } } if (!update) { break; } } // 負閉路のチェック if (update) { for (int jj = 0; jj < edges.size(); jj++) { if (d[edges.get(jj).v] > d[edges.get(jj).u] + edges.get(jj).w) { return -INF; } } } s = i; } return d[j]; } private static class Edge { 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); } } }