#include <iostream>
#include <fstream>
#include <string>
#include <cmath>
#include <cstdio>
#include <algorithm>
#include <iomanip>
#include <vector>
#include <utility>
#include <numeric>
#include <stack>
#include <queue>
#include <map>
#include <set>
#include <unordered_map>
#include <limits.h>
#include <bitset>
#include <math.h>
#define int long long
using namespace std;
using P = pair<int, int>;
using ll = long long;
using prique = priority_queue<int>;
const int INF = LLONG_MAX/3;
const int MAX = 710000;

/*-----Library-----*/

template<class T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return 1; } return 0; }
template<class T> inline bool chmin(T& a, T b) { if (a > b) { a = b; return 1; } return 0; }

struct UnionFind {
    vector<int> par; // 親ノード
    vector<int> rank; // ランク
    vector<int> sizeuf; //要素数
    UnionFind(int n = 1) {
        init(n);
    }

    void init(int n = 1) {
        par.resize(n); rank.resize(n); sizeuf.resize(n);
        for (int i = 0; i < n; ++i) {
            par[i] = i;
            rank[i] = 0;
            sizeuf[i]=1;
        }
    }

    int root(int x) {
        if (par[x] == x) {
            return x;
        }
        else {
            int r = root(par[x]);
            return par[x] = r;
        }
    }

    bool issame(int x, int y) {
        return root(x) == root(y);
    }

    bool merge(int x, int y) {
        x = root(x); y = root(y);
        if (x == y) return false;
        if (rank[x] < rank[y]) swap(x, y);
        if (rank[x] == rank[y]) ++rank[x];
        par[y] = x;
        sizeuf[x]+=sizeuf[y];
        return true;
    }

    int size(int x){
        return sizeuf[root(x)];
    }
};

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

long long lcm(long long i,long long j){
    return i*(j/gcd(i,j));
}
//コンビネーション
/*
long long fac[MAX], finv[MAX], inv[MAX];
// テーブルを作る前処理
void COMinit() {
    fac[0] = fac[1] = 1;
    finv[0] = finv[1] = 1;
    inv[1] = 1;
    for (int i = 2; i < MAX; 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;
    }
}

// 二項係数計算
long long COM(int n, int k){
    if (n < k) return 0;
    if (n < 0 || k < 0) return 0;
    return fac[n] * (finv[k] * finv[n - k] % MOD) % MOD;
}
 */
/*-----Library-----*/
signed main(){
    int n;
    cin>>n;
    vector<pair<int,bool>> s[20];
    for(int i=0;i<n;i++){
        int a;
        cin>>a;
        for(int j=0;j<a;j++){
            int x,y;
            cin>>x>>y;
            if(y==0)s[i].push_back(make_pair(x-1,false));
            else s[i].push_back(make_pair(x-1,true));
        }
    }
    int ans=0;
    for(int i=0;i<(1<<n);i++){
        bool b=true;
        int cnt=0;
        for(int j=0;j<n;j++){
            if(i&(1<<j)){
                cnt++;
                for(int k=0;k<s[j].size();k++){
                    if(s[j][k].second){
                        if(!(i&(1<<s[j][k].first)))b=false;
                    }else{
                        if(i&(1<<s[j][k].first))b=false;
                    }
                }
            }
        }
        if(b)ans=max(cnt,ans);
    }
    cout<<ans<<endl;
    return 0;
}




Measured memory_bytes: 256