/// Containers Start
#include <algorithm>
#include <bitset>
#include <cstdlib>
#include <functional>
#include <iomanip>
#include <iostream>
#include <iterator>
#include <list>
#include <map>
#include <queue>
#include <random>
#include <set>
#include <sstream>
#include <stack>
#include <string>
#include <tuple>
#include <unordered_map>
#include <unordered_set>
#include <utility>
#include <vector>
/// C Header Files
#include <cassert>
#include <cctype>
#include <cmath>
#include <cstdio>
#include <cstring>
#include <ctime>
#include <math.h>
#include <stdio.h>
/// Containers End

using namespace std;

/// Math Start
#define PI acos(-1.0)
#define Pi 3.141592653589793
#define EPS (1e-7)
#define INF (0x3f3f3f3f)
/// Math End

/// Extra Start
#define nn '\n'
#define pb push_back
#define ull unsigned long long
#define ll long long
#define MOD 1000000007
#define sz(a) int((a).size())
#define space " "
#define All(x) (x).begin(), (x).end()
#define rall(x) (x).rbegin(), (x).rend()
/// Extra End

#define rep(i, n) for (int i = 0; i < n; i++)
#define Cini(a)                                                                \
    int a;                                                                     \
    cin >> a;
#define Cinii(a, b)                                                            \
    int a, b;                                                                  \
    cin >> a >> b;
#define Ciniii(a, b, c)                                                        \
    int a, b, c;                                                               \
    cin >> a >> b >> c;
#define Cins(s)                                                                \
    string s;                                                                  \
    cin >> s;
#define Cinss(s1, s2)                                                          \
    string s1, s2;                                                             \
    cin >> s1 >> s2;
#define Cinc(c)                                                                \
    char c;                                                                    \
    cin >> c;
/// Functions End


/// Debug Start
#define deb(x) cout << #x << ": " << x << endl
#define deb2(x, y) cout << #x << ": " << x << '\t' << #y << ": " << y << endl;
#define deb3(x, y, z)                                                          \
    cout << #x << ": " << x << '\t' << #y << ": " << y << '\t' << #z << ": "   \
         << z << endl;
/// Debug End

int dx[] = {-1, 0, 1, 0};
int dy[] = {0, -1, 0, 1};

/**>>>>>>>>>>>>>>>>>>> END <<<<<<<<<<<<<<<<<<**/

/// template


signed main(void) {
    cin.sync_with_stdio(false);
    cin.tie(0);
    Cini(N);
    vector<int> A(N,0);
    vector<vector<int> > targetPerson(N),isTargetHonest(N);
    rep(i,N){
        cin >> A[i];
        rep(j,A[i]){
            int x,y;
            cin >> x >> y;
            x--;
            targetPerson[i].push_back(x);
            isTargetHonest[i].push_back(y);
        }
    }
    vector<int> assumeTargeHonest(N),checkHonestStatus(N);
    int ansMax = 0;
    rep(i,pow(2,N)){
        rep(j,N) assumeTargeHonest[j] = 0,checkHonestStatus[j] = -1;
        rep(j,N){
            assumeTargeHonest[j] = (i>>j)&1;
        }
        bool areThereNoContradictory = true;
        rep(j,N){
            if(checkHonestStatus[j]==-1)checkHonestStatus[j] = assumeTargeHonest[j];
            if(checkHonestStatus[j]!=assumeTargeHonest[j]){
                areThereNoContradictory = false;
                break;
            }else if(checkHonestStatus[j]==0) continue;
            bool isContradictory = false;
            for(const auto& el:targetPerson[j]){
                int index = &el - &targetPerson[j][0];
                if(checkHonestStatus[targetPerson[j][index]]==-1){
                    checkHonestStatus[targetPerson[j][index]] = isTargetHonest[j][index];
                }else{
                    if(checkHonestStatus[targetPerson[j][index]]!=isTargetHonest[j][index]){
                        // 矛盾発見
                        isContradictory = true;
                        break;
                    }
                }
            }
            if(isContradictory){areThereNoContradictory = false; break;}
        }
        if(areThereNoContradictory){
            int totalHonestPeople = 0;
            rep(j,N)if(checkHonestStatus[j]==1)totalHonestPeople++;
            ansMax = max(ansMax,totalHonestPeople);
        }
    }
    cout << ansMax << nn;
    return 0;
}

Measured memory_bytes: 256