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 Python (3.4.3) (judge verdict: Time Limit Exceeded)

import numpy as np
n=int(input())
a=[]
x=np.full((n, n), -1)
p=[]
pp=[[0]*n for i in range(2**n)]
for i in range(n):
    a.append(int(input()))
    for j in range(a[i]):
      X,Y=(map(int,input().split()))
      x[i][X-1]=Y

def rev(x):
    if x ==1:
        return 0
    else:
        return 1
        
def dec2bin(target):
    amari=[]
    while target !=0:
        amari.append(target % 2)
        target = target //2
    if len(amari)!=n:
        while len(amari)!=n:
            amari.append(0)
    amari.reverse()
    return amari

for i in range(2**n):
    p.append(dec2bin(i))
b=[]
for i in range(2**n):
  flag=True
  for j in range(n):
      if p[i][j]==1:
        for k in range(n):
          if( x[j][k]==1 and p[i][k]==0)or (x[j][k]==0 and p[i][k]==1):
            flag=False
            break
        if flag==False:
          break
  if flag:
    b.append(p[i].count(1))
    
            
"""
                elif x[k][1]==0:
                    pp[i][x[k][0]-1]=0
                    
        elif p[i][j]==0:   
            for k in range(a[j]):
                if x[k][1]==0:
                    pp[i][x[k][0]-1]=1
                else:
                    pp[i][x[k][0]-1]=0
"""

if len(b)==0:
  print(0)
else:
  print(max(b))