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 C (GCC 5.4.1) (judge verdict: Runtime Error)

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
int main(int argc,char *argv[])
{
    int N,num[15][15][15],index[15],x[15],count,max=0,bit,flag,flag1;
    char tmp[15]="000000000000000",tmp1[15]="111111111111111",ok[15],ok1[15],temp[15];
    scanf("%d",&N);
    for(int i=0; i<N; i++)
    {
        scanf("%d",&index[i]);
        for(int j=0; j<index[i]; j++)
            scanf("%d%d",&num[i][j][0],&num[i][j][1]);
    }

    strncpy(ok,tmp,N);
    strncpy(ok1,tmp1,N);
    while(strcmp(ok,ok1)!=0)
    {
        flag=0;
        count=0;
        memset(x,0,sizeof(x));
        strcpy(temp,ok);

        for(int i=0; i<N; i++)
            if(ok[i]=='1')
                x[i]=1;
        flag1=1;
        while(flag1==1)
        {
            flag=flag1=0;
            for(int i=0; i<N; i++)
            {

                if(ok[i]=='1')
                {
                    for(int j=0; j<index[i]; j++)
                    {
                        if(num[i][j][1]==0)
                        {
                            if(x[num[i][j][0]-1]==1)
                            {
                                flag=1;
                                break;
                            }
                            else
                                x[num[i][j][0]-1]=0;

                        }
                        else
                        {
                            if(x[num[i][j][0]-1]==0)
                            {
                                flag=1;
                                break;
                            }
                            else
                                x[num[i][j][0]-1]=1;

                        }

                    }
                }
                if(flag==1)
                    break;
            }
            if(flag==1)
                break;
                
            for(int i=0; i<N; i++)
            {
                if(ok[i]!=x[i]+'0')
                    flag1=1;
                ok[i]=x[i]+'0';
            }
        }
        strcpy(ok,temp);

        bit=1;
        while(1)
        {

            if(ok[N-bit]=='0')
            {
                ok[N-bit]++;
                break;
            }
            else
            {
                ok[N-bit]='0';
                bit++;
            }
        }

        if(flag==1)
            continue;

        for(int i=0; i<N; i++)
            if(x[i]==1)
                count++;
        if(count>max)
            max=count;
    }
    printf("%d",max);
    return 0;
}