#include "bits/stdc++.h"
#define rep(i, j) for (int i = 0; i < j; i++)
#define srep(i, j, k) for (int i = j; i < k; i++)
using namespace std;
using ll = long long;
using P = pair<int, int>;
using ull = unsigned long long;

template<class T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return true; } return false; }
template<class T> inline bool chmin(T& a, T b) { if (a > b) { a = b; return true; } return false; }

//エラトステネスの篩
vector<int> estora(vector<int> num) {
    int sel = 0;
    while (sel < num.size()) {
        int d = num[sel];
        for (int i = 0; i < num.size(); i++) {
            if (num[i] % d == 0 && num[i] != d && d != 1) {
                num.erase(num.begin() + i);
                i--;
            }
        }
        sel++;
    }
    return num;
}
/*ライブラリ最大公約数*/
//ユーグリッドの互除法
int gcd(int x, int y) {
    int num[3];
    num[0] = (x > y) ? x : y;
    num[1] = (x <= y) ? x : y;
    num[2] = num[0] % num[1];

    while (num[2]) {
        num[0] = num[1];
        num[1] = num[2];
        num[2] = num[0] % num[1];
    }

    return num[1];
}

/*素因数分解*/
//自作ライブラリ
//iを常に素数にしておかないとうまくできない&&計算量ヤバイ
//エストラネスの篩で素数を振るっておく必要性がありそう
vector<ll> fac(ll n, vector<ll> num) {
    ll kazu = n;
    for (int i = 2; i <= n; i++) {
        while (1) {
            if (kazu % i != 0) break;

            kazu /= i;
            num[i]++;
        }
    }
    if (kazu == n && n != 1)
        num[n]++;
    return num;
    int ans = 0;
    if (kazu != 1) ans++;
    for (int i = 2; i <= sqrt(n); i++) {
        for (int j = 1; j <= num[i]; j++) {
            num[i] -= j;
            ans++;
        }
    }
    return num;
}
const int INF = 1001001001;

//mint用の定数 (10の9乗 + 7)
const int mod = 1000000007;

struct mint {
    ll x; // typedef long long ll;
    mint(ll x = 0) :x((x% mod + mod) % mod) {}
    mint operator-() const { return mint(-x); }
    mint& operator+=(const mint a) {
        if ((x += a.x) >= mod) x -= mod;
        return *this;
    }
    mint& operator-=(const mint a) {
        if ((x += mod - a.x) >= mod) x -= mod;
        return *this;
    }
    mint& operator*=(const mint a) { (x *= a.x) %= mod; return *this; }
    mint operator+(const mint a) const { return mint(*this) += a; }
    mint operator-(const mint a) const { return mint(*this) -= a; }
    mint operator*(const mint a) const { return mint(*this) *= a; }
    mint pow(ll t) const {
        if (!t) return 1;
        mint a = pow(t >> 1);
        a *= a;
        if (t & 1) a *= *this;
        return a;
    }

    // for prime mod
    mint inv() const { return pow(mod - 2); }
    mint& operator/=(const mint a) { return *this *= a.inv(); }
    mint operator/(const mint a) const { return mint(*this) /= a; }
};
istream& operator>>(istream& is, const mint& a) { return is >> a.x; }
ostream& operator<<(ostream& os, const mint& a) { return os << a.x; }

int n;
vector<int> a(0);
vector<vector<P> > xy(0);
int ans = 0;
void dfs(vector<int> a_array) {
    if (a_array.size() == n) {
        int num = 0;
        int ok = 0;
        queue<int> syou;
        rep(i, n) {
            if (a_array[i] == 1) {
                rep(j, a[i]) {
                    if (xy[i][j].second == 1) {
                        a_array[xy[i][j].first] = 1;
                        syou.push(xy[i][j].first);
                    }
                }
            }
        }
        while (!syou.empty()) {
            int c = syou.front(); syou.pop();
            rep(i, a[c]) {
                if (xy[c][i].second == 1) {
                    if (a_array[xy[c][i].first] == 1) continue;
                    a_array[xy[c][i].first] = 1;
                    syou.push(xy[c][i].first);
                }
            }
        }
        rep(i, n) {
            if (a_array[i] == 1) {
                num++;
                rep(j, a[i]) {
                    if (xy[i][j].second == 0) {
                        if (a_array[xy[i][j].first] == 1) {
                            ok = 1;
                        }
                        a_array[xy[i][j].first] = 2;
                    }
                    else {
                        if (a_array[xy[i][j].first] == 2) {
                            ok = 1;
                        }
                        a_array[xy[i][j].first] = 1;
                    }
                }
            }
        }
        if (ok == 0)
            ans = max(ans, num);
    }
    else {
        rep(i, 2) {
            a_array.emplace_back(i);
            dfs(a_array);
            a_array.erase(a_array.begin() + a_array.size() - 1);
        }
    }
}

int main() {
    cin >> n;
    rep(i, n) {
        int num;
        cin >> num;
        a.emplace_back(num);
        vector<P> aa;
        xy.emplace_back(aa);
        rep(j, a[i]) {
            P kari;
            cin >> kari.first >> kari.second;
            kari.first--;
            xy[i].emplace_back(kari);
        }
    }
    vector<int> a_array(0);
    dfs(a_array);
    cout << ans << endl;
    return 0;
}

Measured memory_bytes: 3648