Problem:
Score : 300 points

Problem Statement

There are N people numbered 1 to N. Each of them is either an honest person whose testimonies are always correct or an unkind person whose testimonies may be correct or not.

Person i gives A_i testimonies. The j-th testimony by Person i is represented by two integers x_{ij} and y_{ij}. If y_{ij} = 1, the testimony says Person x_{ij} is honest; if y_{ij} = 0, it says Person x_{ij} is unkind.

How many honest persons can be among those N people at most?

Constraints

All values in input are integers.

1 \leq N \leq 15

0 \leq A_i \leq N - 1

1 \leq x_{ij} \leq N

x_{ij} \neq i

x_{ij_1} \neq x_{ij_2} (j_1 \neq j_2)

y_{ij} = 0, 1

Input

Input is given from Standard Input in the following format:

N
A_1
x_{11} y_{11}
x_{12} y_{12}
:
x_{1A_1} y_{1A_1}
A_2
x_{21} y_{21}
x_{22} y_{22}
:
x_{2A_2} y_{2A_2}
:
A_N
x_{N1} y_{N1}
x_{N2} y_{N2}
:
x_{NA_N} y_{NA_N}

Output

Print the maximum possible number of honest persons among the N people.

Sample Input 1

3
1
2 1
1
1 1
1
2 0

Sample Output 1

2

If Person 1 and Person 2 are honest and Person 3 is unkind, we have two honest persons without inconsistencies, which is the maximum possible number of honest persons.

Sample Input 2

3
2
2 1
3 0
2
3 1
1 0
2
1 1
2 0

Sample Output 2

0

Assuming that one or more of them are honest immediately leads to a contradiction.

Sample Input 3

2
1
2 0
1
1 0

Sample Output 3

1

Solution in JavaScript (node.js v5.12) (judge verdict: Wrong Answer)

inp = require('fs').readFileSync('/dev/stdin', 'utf8').trim().split('\n')
n = inp.shift() * 1
arr = []
max = 0
c = 0
for(i=0;i<n;i++) {
    a = inp.shift() * 1
    arr[i] = new Array(n)
    for(j=0;j<a;j++) {
        l = inp.shift().split(' ')
        x = l[0] - 1
        y = l[1] * 1
        arr[i][x] = y
    }
}

b = []
for(x=Math.pow(2,n)-1;x>=0;x--) {
    ax = new Array(n)
    y = x
    i = 0
    while(y) {
        ax[i] = y % 2
        y >>= 1
        i++
    }
 
    f = 0
    for(i=0;i<n;i++) {
        if (ax[i] != 1) {
            continue;
        } 
        for(j=0;j<n;j++) {
            if (i == j) {
                continue;
            }
            if (arr[i][j] !== undefined) {
                if (ax[j] != arr[i][j]) {
                    f = 1
                    break;
                } 
            }
        }
        if (f) {
            break;
        }
    }
    if (!f) {
        c = ax.filter(x => x == 1).length
        if (max < c) {
            max = c
        }
    }
}
console.log(max)