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.IOException;
import java.io.InputStream;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.NoSuchElementException;

public class Main {
	//FastScannerクラス、普通の Scannerクラスだとメモリと時間を大幅に喰らうので高速化する内部クラス。
	
	public static void main(String[]args) {
		FastScanner sc = new FastScanner(System.in);

		int N = Integer.parseInt(sc.next());
		ArrayList<ArrayList<SG>>deta= new ArrayList<ArrayList<SG>>();
		for(int i = 0;i<N;i++) {
			ArrayList<SG>list = new ArrayList<SG>();
			deta.add(list);
		}
		
		int[]A  = new int[N];
		for(int i = 0;i<N;i++) {
			A[i] = Integer.parseInt(sc.next());
			for(int j = 0;j<A[i];j++) {
				deta.get(i).add(new SG(Integer.parseInt(sc.next()),Integer.parseInt(sc.next())));
			}
		}
		
		int max = 0;
		
		for (int i=0; i<(Math.pow(2,N)); i++) {
			String s ="";
			int []usohon =new int[N]; 
			for (int j=0; j<N; j++) {
				if ((1&i>>j) == 1) {
					s += "1";
					usohon[j]=1;
				}
				else {s+="0";}
			}
			s = "1"+s;
			int shoujiki = digsum(Integer.valueOf(s))-1;
			s = s.substring(1, N+1);
			int []mujun = new int[N];
			int dame = 0;
			Arrays.fill(mujun, -1);
			/*
			outside:for(int z = 0;z<N;z++) {
				if(usohon[z]==0)continue;
				for(int j = 0;j<deta.get(z).size();j++) {
					if(mujun[deta.get(z).get(j).x-1]==-1) {
						mujun[deta.get(z).get(j).x-1]=deta.get(z).get(j).y;
					}
					if(mujun[deta.get(z).get(j).x-1]!=-1&&mujun[deta.get(z).get(j).x-1]!=deta.get(z).get(j).y) {
						dame = 1;
						break outside;
					}
				}
			}*/
			//System.out.println(s);
			
			//System.out.println(dame);
			for(int h = 0;h<N;h++) {
				//System.out.print(mujun[h]);
				//System.out.print(" ");
			}
			//System.out.println();
			
			if(dame==0) {
				
			char []c = s.toCharArray();
			int ok = 1;
			for(int w = 0;w<N;w++) {
				if(mujun[w]==-1)continue;
				if(c[w]!='0'+mujun[w]) {ok=0;
				break;
				
				}
			}
			if(ok==1&&max<shoujiki) {
				//System.out.println(s);
				max = shoujiki;
			}
			
			
			}
			
	
				
	
		}
		System.out.println(max);
		
		/*
		for(int i = 0;i<N;i++) {
			for(int j = 0;j<deta.get(i).size();j++) {
				System.out.print(deta.get(i).get(j).x);
				System.out.print(" ");
				System.out.print(deta.get(i).get(j).y);
				System.out.println();
			}
			System.out.println();
		}
		*/
		
	
	
	
	
	
	}
	
	
	private static int digsum(int n) {//数字ｎの桁和
		int res = 0;
		while(n>0) {
			res+=n%10;//10で割った余りは一の位の桁に等しい
			n/=10;//一桁入れ終わったので削除
		}
		return res;
	}
	
	
	
	static class SG{
		int x;
		int y;
		SG(int X,int Y){
			x = X;y = Y;
		}
	}
	
	
	
	static class FastScanner {
		 
		private final InputStream in;
		private final byte[] buffer = new byte[1024];
		private int ptr = 0;
		private int buflen = 0;
 
		public FastScanner(InputStream source) {
			in = source;
		}
 
		private boolean hasNextByte() {
			if (ptr < buflen) {
				return true;
			} else {
				ptr = 0;
				try {
					buflen = in.read(buffer);
				} catch (IOException e) {
					e.printStackTrace();
				}
				if (buflen <= 0) {
					return false;
				}
			}
			return true;
		}
 
		private int readByte() {
			if (hasNextByte()) return buffer[ptr++];
			else return -1;
		}
 
		private static boolean isPrintableChar(int c) {
			return 33 <= c && c <= 126;
		}
 
		private void skipUnprintable() {
			while (hasNextByte() && !isPrintableChar(buffer[ptr])) ptr++;
		}
 
		public boolean hasNext() {
			skipUnprintable();
			return hasNextByte();
		}
 
		public String next() {
			if (!hasNext()) throw new NoSuchElementException();
			StringBuilder sb = new StringBuilder();
			int b = readByte();
			while (isPrintableChar(b)) {
				sb.appendCodePoint(b);
				b = readByte();
			}
			return sb.toString();
		}
 
		public long nextLong() {
			if (!hasNext()) throw new NoSuchElementException();
			long n = 0;
			boolean minus = false;
			int b = readByte();
			if (b == '-') {
				minus = true;
				b = readByte();
			}
			if (b < '0' || '9' < b) {
				throw new NumberFormatException();
			}
			while (true) {
				if ('0' <= b && b <= '9') {
					n *= 10;
					n += b - '0';
				} else if (b == -1 || !isPrintableChar(b)) {
					return minus ? -n : n;
				} else {
					throw new NumberFormatException();
				}
				b = readByte();
			}
		}
	}

}