#include<iostream>
#include<vector>
#include<string>
#include<algorithm>
#include<cmath>
#include<bitset>
#include<deque>
#include<functional>
#include<iterator>
#include<map>
#include<set>
#include<stack>
#include<queue>
#include<utility>
using namespace std;
typedef long long ll;
typedef pair<ll,ll> P;
#define a first
#define b second
#define sz(x) (ll)((x).size())
#define pb push_back
#define mp make_pair
#define bg begin()
#define ed end()
#define all(x) (x).bg,(x).ed
#define rep(i,n) for(ll i=0;i<(n);i++)
#define rep1(i,n) for(ll i=1;i<=(n);i++)
#define rrep(i,n) for(ll i=(n)-1;i>=0;i--)
#define rrep1(i,n) for(ll i=(n);i>=1;i--)
#define FOR(i,a,b) for(ll i=(a);i<(b);i++)
const ll MOD=1000000007;
const ll INF=1000000000000000;
template<class T> inline bool chmin(T& a, T b){if(a>b){a=b;return true;}return false;}
template<class T> inline bool chmax(T& a, T b){if(a<b){a=b;return true;}return false;}
ll maxx(ll x,ll y,ll z){return max(max(x,y),z);}
ll minn(ll x,ll y,ll z){return min(min(x,y),z);}
ll gcd(ll x,ll y){if(x%y==0) return y;else return gcd(y,x%y);}
ll lcm(ll x,ll y){return x*(y/gcd(x,y));}
ll digsz(ll x){if(x==0) return 1;else{ll ans=0;while(x){x/=10;ans++;}return ans;}}
ll digsum(ll x){ll sum=0;while(x){sum+=x%10;x/=10;}return sum;}
vector<ll> pw2(62,1);vector<ll> pw10(19,1);
vector<ll> vectorprime(ll x){
    vector<bool> is_prime(x+1);
    vector<ll> prime;
    rep(i,x+1) is_prime[i]=true;
    is_prime[0]=is_prime[1]=false;
    for(ll i=2;i<=x;i++){
        if(is_prime[i]){
            prime.pb(i);
        }
        for(int j=i*2;j<=x;j+=i) is_prime[j]=false;
    }
    return prime;
}
map<ll,ll> prime_factor(ll x){
    map<ll,ll> m;
    ll sq=(ll)sqrt(x) + 1;
    vector<ll> v_prime=vectorprime(sq);
    
    ll tmp=x;
    rep(i,sz(v_prime)){
        ll count=0;
        while(tmp % v_prime[i] == 0){
            tmp /= v_prime[i];
            count++;
        }
        if(count != 0) m[v_prime[i]]=count;
        if(tmp==1) break;
    }
    
    if(tmp != 1) m[tmp]=1;
    return m;
}
ll fac[500001],finv[500001],inv[500001];
 
void table() {
    fac[0]=fac[1]=1;
    finv[0]=finv[1]=1;
    inv[1]=1;
    for(ll i=2;i<500001;i++){
        fac[i]= fac[i-1]*i%MOD;
        inv[i]=MOD-inv[MOD%i]*(MOD/i)%MOD;
        finv[i]=finv[i-1]*inv[i]%MOD;
    }
}

ll dev(long long a,long long b){
    return (a*inv[b])%MOD;
}

ll comb(ll n, ll k){
    if(n<k) return 0;
    if(n<0 || k<0) return 0;
    return fac[n]*(finv[k]*finv[n-k]%MOD)%MOD;
}

int main(){
    table();
    {rep1(i,61) pw2[i]=2*pw2[i-1];}
    {rep1(i,18) pw10[i]=10*pw10[i-1];}
    
    ll N; cin>>N;
    vector<ll> A(16,0);
    vector<vector<ll> > x(16,vector<ll>(16,0));
    vector<vector<ll> > y(16,vector<ll>(16,0));
    
    rep1(i,N){
        cin>>A[i];
        rep1(j,A[i]){
            cin>>x[i][j]>>y[i][j];
        }
    }
    ll ans=0;
    
    rep(i,pw2[N]){
        //BIT全探索
        vector<ll> BIT(N);
        ll tmps=i;
        rrep(i2,N){
            BIT[i2]=tmps/pw2[i2];
            tmps%=pw2[i2];
        }
            
        bool c=true;
        rep1(j,N){
            //jが正直
            if(BIT[j-1]==1){
                rep1(k,A[j]){
                    if(BIT[x[j][k] -1]!=y[j][k]){
                        c=false;
                    }
                }
            }
        }
        if(c){
            ll cnt=0;
            rep(i2,N){
                if(BIT[i2]==1) cnt++;
            }
            chmax(ans,cnt);
        }
    }
    cout<<ans<<endl;
}



Measured memory_bytes: 15448