#include <bits/stdc++.h>
using namespace std;

typedef struct lol {
  int x, y, z;
} troll;

int a[3505], i, j, rs, t, n, arb[3505][3505];
troll c[3505];

bool cmp(const troll & a, const troll & b) {
  return a.z < b.z;
}

int query(int x, int y) {
  int rs = 0;
  for (int i = x; i >= 1; i -= -i & i)
    for (int j = y; j >= 1; j -= -j & j)
      rs = max(rs, arb[i][j]);
  return rs;
}

void update(int x, int y, int z) {
  for (int i = x; i <= n; i += -i & i)
    for (int j = y; j <= n; j += -j & j)
      if (z > arb[i][j]) arb[i][j] = z;
}

int main() {
  cin >> n;
  for(t = 1; t > 0; --t) {
    for (i = 1; i <= n; ++i)
      cin >> c[i].x >> c[i].y >> c[i].z;

    sort(c + 1, c + n + 1, cmp);

    for (rs = 1, i = 1; i <= n; ++i)
      a[i] = query(c[i].x, c[i].y) + 1,
      update(c[i].x, c[i].y, a[i]), rs = max(rs, a[i]);

    cout << rs << '\n';
  }

  return 0;
}