#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using Edge = pair<int, int>;
using Graph = vector<vector<Edge>>;
#define REP(i, n) for (int i = 0; i < (n); ++i)
#define SORT(v) sort((v).begin(), (v).end())
#define RSORT(v) sort((v).rbegin(), (v).rend())
const ll MOD = 1000000007;
const ll nmax = 8;
const ll INF = 1e9;
bool graph[nmax][nmax];
vector<vector<ll>> dist = vector<vector<ll>>(nmax, vector<ll>(nmax, INF));
void warshall_floyd(ll n)
{
    for (size_t i = 0; i < n; i++)
    {
        for (size_t j = 0; j < n; j++)
        {
            for (size_t k = 0; k < n; k++)
            {
                dist[j][k] = min(dist[j][k], dist[j][i] + dist[i][k]);
            }
        }
    }
}

class UnionFind
{
public:
    vector<ll> Parent;

    UnionFind(ll N)
    {
        Parent = vector<ll>(N, -1);
    }
    ll find(ll A)
    {
        if (Parent[A] < 0)
            return A;
        return Parent[A] = find(Parent[A]);
    }

    ll size(ll A)
    {
        return -Parent[find(A)];
    }

    bool Union(ll A, ll B)
    {
        A = find(A);
        B = find(B);
        if (A == B)
        {
            return false;
        }
        if (size(A) < size(B))
            swap(A, B);

        Parent[A] += Parent[B];
        Parent[B] = A;

        return true;
    }
};

ll gcd(ll a, ll b)
{
    if (b == 0)
        return a;
    return gcd(b, a % b);
}

ll lcm(ll a, ll b)
{
    ll g = gcd(a, b);
    return a / g * b;
}

ll mulMod(ll a, ll b)
{
    return (((a % MOD) * (b % MOD)) % MOD);
}

ll powMod(ll a, ll p)
{
    if (p == 0)
    {
        return 1;
    }
    else if (p % 2 == 0)
    {
        ll half = powMod(a, p / 2);
        return mulMod(half, half);
    }
    else
    {
        return mulMod(powMod(a, p - 1), a);
    }
}

ll ceil(ll a, ll b)
{
    return (a + b - 1) / b;
}

int main()
{
    ll N;
    cin >> N;
    vector<vector<pair<ll, ll>>> A(N);

    for (ll i = 0; i < N; ++i)
    {
        ll a;
        cin >> a;
        for (ll j = 0; j < a; j++)
        {
            ll x, y;
            cin >> x >> y;
            A[i].push_back(make_pair(x, y));
        }
    }
    ll ans = 0;
    for (ll bit = 0; bit < (1 << N); ++bit)
    {
        bool perfect = true;
        ll cnt = 0;
        for (ll i = 0; i < N; ++i)
        {
            if (bit & (1 << i))
            {
                cnt++;
            }
            for (auto &&j : A[i])
            {
                if (bit & (1 << i))
                {
                    // iは正直者
                    if (j.second == 1)
                    {
                        //jは正直者のはず
                        if (!(bit & (1 << j.first - 1)))
                        {
                            perfect = false;
                        }
                    }
                    else
                    {
                        //jは不親切のはず
                        if (bit & (1 << j.first - 1))
                        {
                            perfect = false;
                        }
                    }
                }
                else
                {
                    //　iは不親切
                    // if (j.second == 1)
                    // {
                    //     //jは不親切のはず
                    //     if (bit & (1 << j.first - 1))
                    //     {
                    //         perfect = false;
                    //     }
                    // }
                    // else
                    // {
                    //     //jは正直者
                    //     if (!(bit & (1 << j.first - 1)))
                    //     {
                    //         perfect = false;
                    //     }
                    // }
                }
            }
        }
        if (perfect)
        {
            ans = max(ans, cnt);
        }
    }
    cout << ans << endl;

    return 0;
}


Measured memory_bytes: 256