Buggy python submission (verdict: Time Limit Exceeded):
import numpy as np

N = int(input())
A = np.zeros((N,2,N), dtype=bool) # A = {([false],[true]),,}

for i in range(N):
  for j in range(int(input())):
  	x, y = map(int,input().split())
  	A[i][y][x-1] = True

upper = 0

for i in range(2**N):
  mask = (1 & i >> np.arange(N)).astype(bool)
  s = np.sum(mask)
  if s <= upper: continue
  m2 = np.repeat([mask], s, axis=0).reshape(-1)
  aa = A[mask]
  a0 = aa[:,0].reshape(-1)
  if np.any(m2[a0]!=0): continue
  a1 = aa[:,1].reshape(-1)
  if np.any(m2[a1]!=1): continue
  upper = s

print(upper)

Fixed submission:
import numpy as np

N = int(input())
A = np.zeros((N,2,N), dtype=bool) # A = {([false],[true]),,}

for i in range(N):
  for j in range(int(input())):
  	x, y = map(int,input().split())
  	A[i][y][x-1] = True

upper = 0

def hantei(mask):
  for a in A[mask]:
    if np.any(mask[a[0]]): return False
    if not(np.all(mask[a[1]])): return False
  return True

seed = 1 << np.arange(N)

for i in range(2**N):
  mask = (seed & i).astype(bool)
  s = np.sum(mask)
  if s <= upper: continue
  if hantei(mask): upper = s

print(upper)

Buggy python submission (verdict: Time Limit Exceeded):
import numpy as np

N = int(input())
A = np.zeros((N,2,N), dtype=bool) # A = {([false],[true]),,}

for i in range(N):
  for j in range(int(input())):
  	x, y = map(int,input().split())
  	A[i][y][x-1] = True

upper = 0

seed = 1 << np.arange(N)

for i in range(2**N):
  mask = (seed & i).astype(bool)
  s = np.sum(mask)
  if s <= upper: continue
  m2 = np.repeat([mask], s, axis=0).reshape(-1)
  aa = A[mask]
  a0 = aa[:,0].reshape(-1)
  if np.any(m2[a0]!=0): continue
  a1 = aa[:,1].reshape(-1)
  if np.any(m2[a1]!=1): continue
  upper = s

print(upper)

Fixed submission:
import numpy as np

N = int(input())
A = np.zeros((N,2,N), dtype=bool) # A = {([false],[true]),,}

for i in range(N):
  for j in range(int(input())):
  	x, y = map(int,input().split())
  	A[i][y][x-1] = True

upper = 0

def hantei(mask):
  for a in A[mask]:
    if np.any(mask[a[0]]): return False
    if not(np.all(mask[a[1]])): return False
  return True

seed = 1 << np.arange(N)

for i in range(2**N):
  mask = (seed & i).astype(bool)
  s = np.sum(mask)
  if s <= upper: continue
  if hantei(mask): upper = s

print(upper)

Buggy python submission (verdict: Time Limit Exceeded):
import numpy as np

N = int(input())
A = np.zeros((N,2,N), dtype=bool) # A = {([false],[true]),,}

for i in range(N):
  for j in range(int(input())):
  	x, y = map(int,input().split())
  	A[i][y][x-1] = True

upper = 0

def hantei(mask,s):
  m2 = np.repeat([mask], s, axis=0).reshape(-1)
  aa = A[mask]
  a0 = aa[:,0].reshape(-1)
  if np.any(m2[a0]!=0): return False
  a1 = aa[:,1].reshape(-1)
  if np.any(m2[a1]!=1): return False
  return True

seed = 1 << np.arange(N)

for i in range(2**N):
  mask = (seed & i).astype(bool)
  s = np.sum(mask)
  if s <= upper: continue
  if hantei(mask,s): upper = s

print(upper)

Fixed submission:
import numpy as np

N = int(input())
A = np.zeros((N,2,N), dtype=bool) # A = {([false],[true]),,}

for i in range(N):
  for j in range(int(input())):
  	x, y = map(int,input().split())
  	A[i][y][x-1] = True

upper = 0

def hantei(mask):
  for a in A[mask]:
    if np.any(mask[a[0]]): return False
    if not(np.all(mask[a[1]])): return False
  return True

seed = 1 << np.arange(N)

for i in range(2**N):
  mask = (seed & i).astype(bool)
  s = np.sum(mask)
  if s <= upper: continue
  if hantei(mask): upper = s

print(upper)

Buggy python submission (verdict: Time Limit Exceeded):
import numpy as np

N = int(input())
A = np.zeros((N,2,N), dtype=bool) # A = {([false],[true]),,}

for i in range(N):
  for j in range(int(input())):
  	x, y = map(int,input().split())
  	A[i][y][x-1] = True

upper = 0

def hantei(mask):
  for a in A[mask]:
    if np.any(mask[a[0]]!=0): return False
    if np.any(mask[a[1]]!=1): return False
  return True

seed = 1 << np.arange(N)

for i in range(2**N):
  mask = (seed & i).astype(bool)
  s = np.sum(mask)
  if s <= upper: continue
  if hantei(mask): upper = s

print(upper)

Fixed submission:
import numpy as np

N = int(input())
A = np.zeros((N,2,N), dtype=bool) # A = {([false],[true]),,}

for i in range(N):
  for j in range(int(input())):
  	x, y = map(int,input().split())
  	A[i][y][x-1] = True

upper = 0

def hantei(mask):
  for a in A[mask]:
    if np.any(mask[a[0]]): return False
    if not(np.all(mask[a[1]])): return False
  return True

seed = 1 << np.arange(N)

for i in range(2**N):
  mask = (seed & i).astype(bool)
  s = np.sum(mask)
  if s <= upper: continue
  if hantei(mask): upper = s

print(upper)