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 Java8 (OpenJDK 1.8.0) (judge verdict: Runtime Error)

import java.io.*;
import java.util.*;

public class Main {
	public static void main(String[] args) throws IOException {
		try (BufferedReader in =
new BufferedReader(new InputStreamReader(System.in))) {
			
String line;
line = in.readLine();

int n = Integer.parseInt(line);

int[][] sayTable = new int[n][];
for (int i = 0; i < n; ++i) {
line = in.readLine();
int a = Integer.parseInt(line);
sayTable[i] = new int[a];
for (int j = 0; j < a; ++j) {
line = in.readLine();
String[] params = line.split(" ");
	int x = Integer.parseInt(params[0]) - 1;
	int y = Integer.parseInt(params[1]);
		sayTable[i][x] = y + 1;
	}
}
int maxHonest = search(sayTable, new int[n], 0);
System.out.println(maxHonest);
}
	}

	public static int search(
int[][] sayTable, int[] honest, int i) {

		if (i >= sayTable.length) {
			return (int) Arrays.stream(honest)
.filter(say -> say == 2)
.count();
		}

		int[] sayArray = sayTable[i];

		int count = 0;
		if (checkHonest(honest, sayArray)) {
	int[] copyHonest = Arrays.copyOf(honest, honest.length);
	setHonest(copyHonest, sayArray);
int c = search(sayTable, copyHonest, i + 1);
count = Math.max(c, count);
	}
		if (checkUnkind(honest, sayArray)) {
		int[] copyHonest = Arrays.copyOf(honest, honest.length);
setUnkind(copyHonest, sayArray);
int c = search(sayTable, copyHonest, i + 1);
count = Math.max(c, count);
	}
return count;
}



	public static boolean checkHonest(int[] honest, int[] sayArray) {
		for (int i = 0; i < sayArray.length; ++i) {
			int say = sayArray[i];
			if (say <= 0) {
				continue;
			}
			int h = honest[i];
			if (h != 0 || h != say) {
return false;				
			}
		}
return true;
	}

	public static boolean checkUnkind(int[] honest, int[] sayArray) {
		for (int i = 0; i < sayArray.length; ++i) {
			int say = sayArray[i];
			if (say <= 0) {
				continue;
			}
			int h = honest[i];
			if (h != 0 || h == say) {
return false;				
			}
		}
return true;
	}

public static void setHonest(int[] honest, int[] sayArray) {
		for (int i = 0; i < sayArray.length; ++i) {
			int say = sayArray[i];
			if (say == 1) {
				honest[i] = 1;
			} else if (say == 2) {
				honest[i] = 2;
			}
		}
	}

	public static void setUnkind(int[] honest, int[] sayArray) {
		for (int i = 0; i < sayArray.length; ++i) {
			int say = sayArray[i];
			if (say == 1) {
				honest[i] = 2;
			} else if (say == 2) {
				honest[i] = 1;
			}
		}
	}
}