//
// Created by Mahmoud Rashad on 11/27/19.
//


#include <bits/stdc++.h>

using namespace std;

typedef vector<pair<int, bool>> vii;

int main(){

    int n;
    cin >> n;
    vector<vii> data(n, vii());
    for (int i = 0; i < n; ++i) {
        int a;
        cin >> a;
        while (a--) {
            int u;
            bool kind;
            cin >> u >> kind;
            data[i].push_back({--u, kind});
        }
    }


    int ans = 0;
    for(int mask = 0; mask < (1 << n); ++mask) {
        bool f = true;
        for (int i = 0; i < n; ++i) {
            if (!(mask & (1 << i)))
                continue;
            for (auto &p : data[i]) {
                int u = p.first;
                bool kind = p.second;
//                cout << mask << ' ' << u << ' ' << kind << endl;
                f &= ((bool)(mask & (1 << u)) == kind);
            }
        }
//        cout << mask << ' ' << f << endl;
        ans = max(ans, __builtin_popcount(mask) * f);
    }


    cout << ans << '\n';

    return 0;
}