#pragma region

#include <bits/stdc++.h>
using namespace std;
#define ALL(x) (x).begin(), (x).end()
#define POW2(n) (1LL << (n))
#define FOR(i, begin, end) for (int i = (begin); i < (end); i++)
#define IFOR(i, begin, end) for (int i = (end)-1; i >= (begin); i--)
#define REP(i, n) FOR(i, 0, n)
#define IREP(i, n) IFOR(i, 0, n)
#define MOD 1000000007
#define debug(x) cerr << #x << " = " << (x) << " (line: " << __LINE__ << ") " << endl;
typedef long long ll;
template <typename T>
istream &operator>>(istream &is, vector<T> &vec) {
  for (auto &v : vec) is >> v;
  return is;
}
template <typename T>
ostream &operator<<(ostream &os, const vector<T> &vec) {
  os << "vec[ ";
  REP(i, vec.size())
  i == 0
      ? os << vec[i]
      : os << ", " << vec[i];
  os << " ]";
  return os;
}
template <typename T>
ostream &operator<<(ostream &os, const deque<T> &deq) {
  os << "deq[ ";
  REP(i, deq.size())
  i == 0
      ? os << deq[i]
      : os << ", " << deq[i];
  os << " ]";
  return os;
}
template <typename T>
ostream &operator<<(ostream &os, const set<T> &set) {
  os << "{ ";
  for (auto &&s : set) &s == &(*set.begin()) ? os << s : os << ", " << s;
  os << " }";
  return os;
}
template <typename T>
ostream &operator<<(ostream &os, const unordered_set<T> &set) {
  os << "{ ";
  for (auto &&s : set) &s == &(*set.begin()) ? os << s : os << ", " << s;
  os << " }";
  return os;
}
template <typename T>
ostream &operator<<(ostream &os, const multiset<T> &set) {
  os << "{ ";
  for (auto &&s : set) &s == &(*set.begin()) ? os << s : os << ", " << s;
  os << " }";
  return os;
}
template <typename T>
ostream &operator<<(ostream &os, const unordered_multiset<T> &set) {
  os << "{ ";
  for (auto &&s : set) &s == &(*set.begin()) ? os << s : os << ", " << s;
  os << " }";
  return os;
}
template <typename T1, typename T2>
ostream &operator<<(ostream &os, const pair<T1, T2> &p) {
  os << "(" << p.first << ", " << p.second << ")";
  return os;
}
template <typename TK, typename TV>
ostream &operator<<(ostream &os, const map<TK, TV> &m) {
  os << "{ ";
  for (auto &&k : m) &k == &(*m.begin()) ? os << k.first << " => " << k.second : os << ", " << k.first << " => " << k.second;
  os << " }";
  return os;
}
template <typename TK, typename TV>
ostream &operator<<(ostream &os, const unordered_map<TK, TV> &m) {
  os << "{ ";
  for (auto &&k : m) &k == &(*m.begin()) ? os << k.first << " => " << k.second : os << ", " << k.first << " => " << k.second;
  os << " }";
  return os;
}

#pragma endregion

int main() {
  cin.tie(0);
  ios::sync_with_stdio(false);
  cout << fixed << setprecision(16);

  int N;
  cin >> N;
  vector<vector<pair<short, bool>>> A(N);
  REP(i, N) {
    int a;
    cin >> a;
    A[i] = vector<pair<short, bool>>(a);
    REP(j, a) {
      int x, y;
      cin >> x >> y;
      A[i][j] = make_pair<short, bool>(x - 1, y);
    }
  }

  int max = 0;
  bool cont = true;
  REP(i, 1 << N) {
    cont = true;
    REP(j, N) {
      if (!cont) break;
      REP(k, A[j].size()) {
        if ((i & (1 << j)) && (bool)(i & (1 << A[j][k].first)) ^ A[j][k].second) {
          cont = false;
          break;
        }
      }
    }
    if (cont) {
      int c = 0;
      REP(l, N)
      if ((i >> l) & 1) c++;
      if (max < c) max = c;
    }
  }

  cout << max << endl;
}


Measured memory_bytes: 256