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 Julia (0.5.0) (judge verdict: Wrong Answer)

parseInt(x) = parse(Int, x)
parseMap(x::Array{SubString{String},1}) = map(parseInt, x)

function carry(x::Array{Int,1},n)
	k = length(x)
	for i in 1:k-1
		if x[k-i+1] > n-1
			x[k-i] += div(x[k-i+1],n)
			x[k-i+1] = x[k-i+1]%n
		end
	end
	if x[1] > n-1
		0
	else
		x
	end
end

function main()
	n = readline() |> parseInt
	a = [zeros(Int,n) for i in 1:n]
	for i in 1:n
		x = readline() |> parseInt
		a[i][i] = 1
		for j in 1:x
			p,q = readline() |> split |> parseMap
			if q == 1
				a[i][p] = 1
			else
				a[i][p] = -1
			end
		end
	end
	ct = 0
	z = zeros(Int,n)
	while z!=0
		f = 0
		ans = z[1]==0?-copy(a[1]):copy(a[1])
		for i in 2:n
			tmp = z[i]==0?-copy(a[i]):copy(a[i])
			for j in 1:n
				if ans[j]==0
					ans[j] = tmp[j]
				elseif tmp[j]!=0&&tmp[j]!=ans[j]
					f = 1
				end
			end
		end
		if f == 0
			ct = max(ct,sum(z))
		end
		z[n] += 1
		z=carry(z,2)
	end
	println(ct)
end

main()