#include <bits/stdc++.h>
#pragma GCC optimize("Ofast")
#pragma GCC optimize("unroll-loops")
#pragma GCC target("sse2")

    /*
    ||||||||||||||||||||||||||||||||||||||||||||||||
       |      |||         |      ||||    ||||  |   |
      | |     |   |      | |     |   |  |      |   |
     |   |    |    |    |   |    |   |  |      |   |
    |||||||   |    |   |||||||   |||     |||   |||||
    |     |   |   |    |     |   | |        |  |   |
    |     |   |||      |     |   |  ||  ||||   |   |
    ||||||||||||||||||||||||||||||||||||||||||||||||

    */
    using namespace std;
    //#include "testlib.h"
    #define ff first
    #define ss second
    #define mp make_pair
    #define all(v) v.begin(),v.end()
    #define int long long
    #define ll long long
    #define M 1000000007
    #define inputarr(a,n) for(int i=0;i<n;++i) cin>>a[i]
    #define GCD(m,n) __gcd(m,n)
    #define LCM(m,n) m*(n/GCD(m,n))
    #define mii  map<ll ,ll >
    #define sz(a) (int)a.size()
    #define msi  map<string,ll >
    #define mis  map<ll int, string>
    #define rep(a,b)    for(ll i=a;i<b;i++)
    #define rep0(n)    for(ll i=0;i<n;i++)
    #define repi(i,a,b) for(ll i=a;i<b;i++)
    #define pb push_back
    #define vi vector<ll>
    #define mp make_pair
    #define vs vector<string>
    #define ppb pop_back
    #define endl '\n'
    #define asdf ios_base::sync_with_stdio(false);cin.tie(0);cout.tie(0);
    #define r0 return 0;
    #define FORD(i, a, b) for (int i = (int) (a); i >= (int) (b); --i)
    #define FORE(it, c) for (__typeof((c).begin()) it = (c).begin(); it != (c).end(); ++it)
    #define inputoutput freopen("input.txt", "r", stdin);freopen("output.txt", "w", stdout);
    #define input freopen("input.txt", "r", stdin);
    #define Set(a, s) 4(a, s, sizeof (a))
    #define FOR repi
    #define pii pair<int,int>
    #define REVERSE(v) reverse(ALL(v))
    #define display(x) trav(a,x) cout<<a<<" ";cout<<endl
    #define debug cerr<<"bhau"<<endl
    #define trace(...) __f(#__VA_ARGS__, __VA_ARGS__)
    template <typename Arg1>
    void __f(const char* name, Arg1&& arg1){
        std::cerr << name << " : " << arg1 << endl;
    }
    template <typename Arg1, typename... Args>
    void __f(const char* names, Arg1&& arg1, Args&&... args){
        const char* comma = strchr(names + 1, ',');std::cerr.write(names, comma - names) << " : " << arg1<<" | ";__f(comma+1, args...);
    }
    ll max(ll a, ll b) { return (a > b)? a : b;}
    int min(int a, int b) { return (a < b)? a : b;}
    void amax(int &a,int b){a=max(a,b)%M; }
    void amin(int &a,int b){ a=min(a,b)%M;}
    void inc(int &a,int b){a=(a+b)%M;}
    void dec(int &a,int b){a=(a-b+M)%M;}
    int n;
    const int MAXN=20;
    vector<pii> x[MAXN];
    int y[MAXN];
    int ans=0;
    void find(int p){
    	if(p==n){
    		rep0(n){
    			if(y[i]==1){
    				for(auto j:x[i]){
    					if(y[j.ff]*j.ss==-1){
    						return;
    					}
    				}
    			}
    		}
    		int count=0;
    		rep0(n)if(y[i]==1) count++;
    		// trace(count);
    		ans=max(ans,count);
    		return;
    	}
    	y[p]=1;
    	find(p+1);
    	y[p]=-1;
    	find(p+1);
    }
     int solve()
     {  
     	cin>>n;
     	rep0(n){
     		int a;cin>>a;
     		while(a--){
     			int u,v;cin>>u>>v;u--;
     			if(v==0) v=-1;
     			x[i].pb({u,v});
     		}
     	}
     	y[0]=1;
     	find(1);
     	y[0]=-1;
     	find(1);
     	cout<<ans<<endl;


        r0   
     }
    signed main()
    {   
        asdf
        
        int t=1;
        //cin>>t;
        while(t--)
        {
            solve();
        }     
        
}

Measured memory_bytes: 256