/*
author: Apoorv Singh
*/
 
#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
#include <ext/pb_ds/detail/standard_policies.hpp>
using namespace std;
using namespace __gnu_pbds;
 
typedef vector <long long> vi;
typedef pair <long long, long long> pii;
#define pb push_back   
#define all(c) c.begin(), c.end()
#define For(i, a, b) for (long long i = a; i < b; ++i)
#define Forr(i, a, b) for (long long i = a; i > b; --i)
#define um unordered_map
#define F first
#define S second
#define int long long
#define inf LLONG_MAX
#define endl "\n"
#define min(a,b) (a < b ? a : b)
#define max(a,b) (a > b ? a : b)
#pragma comment(linker, "/stack:200000000")
#pragma GCC optimize ("O3")
#pragma GCC optimize ("unroll-loops")
#pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,tune=native")
#define _CRT_SECURE_NO_WARNINGS
#define fast_io() ios_base::sync_with_stdio(false);cin.tie(NULL);cout.tie(NULL);
 
#define TRACE
#ifndef ONLINE_JUDGE
#define trace(...) __f(#__VA_ARGS__, __VA_ARGS__)
template <typename Arg1>
void __f(const char* name, Arg1&& arg1) {
        cout << name << " : " << arg1 << endl;  
}
template <typename Arg1, typename... Args>
void __f(const char* names, Arg1&& arg1, Args&&... args) {
        const char* comma = strchr(names + 1, ',');cout.write(names, comma - names) << " : " << arg1<<" | ";__f(comma+1, args...);
}
#else
#define trace(...)
#endif
 
template <class X>
void printarr(X arr[], int n) 
{
    for (int i = 0; i < n; ++i)
        cout << arr[i] << ' ';
    cout << endl;
}
 
template <typename X> ostream& operator << (ostream& x,const vector<X>& v){ for (X a : v) x << a << ' '; return x;} 
template <typename X, typename Y> ostream& operator << (ostream& x, const vector< pair<X, Y> >& v) {for (pair <X, Y> it : v) x << it.first << ' ' << it.second << endl; return x;} 
template <typename T, typename S> ostream& operator << (ostream& os, const map<T, S>& v) { for (pair <T, S> it : v) os << it.first << " => " << it.second << endl; return os; }
 
template <class T, class cmp = less<T>> using ordered_set = tree<T, null_type, cmp, rb_tree_tag, tree_order_statistics_node_update>;
 
int modulo = 1e9 + 7;
 
int fpow(int a, int n) 
{
    int ans = 1;
    while (n)
    {
        if (n&1)
            ans = ans*a;
        a = a*a;
        n = n >> 1;
    }
    return ans;
}
 
signed main() 
{
    fast_io();
    int n; cin >> n;
    int M = (1ll << n);
    vector <pii> test[n];
    For(i,0,n) {
        int a; cin >> a;
        For(j,0,a) {
            int x,y; cin >> x >> y;
            test[i].pb({x,y});
        }
    }
    int ans = 0;
    For(i,0,M) {
        int f[n] = {0};
        For(j,0,n) {
            int a = ((i&(1ll << j)));  
            if (a) f[j] = 1;
        }
        bool possible = true;
        int count = 0;
        For(j,0,n) count += f[j];
        For(j,0,n) {
            if (!f[j]) continue;
            for (pii a : test[j]) {
                int x = a.F, y = a.S; --x;
                if (f[x] != y) {
                    possible = false;
                    break;
                }
            }
            if (!possible) break;
        }
        if (possible) ans = max(ans, count);
    }
    cout << ans;
    return 0;
}

Measured memory_bytes: 384