#include <cstdio>

#include <cstring>

#include <iostream>

#include <vector>

using namespace std;

typedef long long ll;

const ll P=1000000007;

ll ans;

int n,S;

vector<int> pa[20],pb[20];

ll v[20][20];

inline int rd()

{

	int ret=0,f=1;	char gc=getchar();

	while(gc<'0'||gc>'9')	{if(gc=='-')	f=-f;	gc=getchar();}

	while(gc>='0'&&gc<='9')	ret=ret*10+gc-'0',gc=getchar();

	return ret*f;

}

ll calc()

{

	int i,j,k;

	ll A,B,tmp,temp,ret=1;

	memset(v,0,sizeof(v));

	for(i=1;i<n;i++)	if((S>>(i-1))&1)	for(j=0;j<(int)pa[i].size();j++)

		A=pa[i][j],B=pb[i][j],v[A][B]--,v[B][A]--,v[A][A]++,v[B][B]++;

	for(i=1;i<=n;i++)	for(j=1;j<=n;j++)	if(v[i][j]<0)	v[i][j]+=P;

	for(i=1;i<n;i++)

	{

		for(j=i+1;j<n;j++)

		{

			A=v[i][i],B=v[j][i];

			while(B)

			{

				tmp=A/B,temp=A,A=B,B=temp%B;

				for(ret=P-ret,k=i;k<n;k++)	v[i][k]=(v[i][k]-tmp*v[j][k]%P+P)%P,swap(v[i][k],v[j][k]);

			}

		}

		ret=ret*v[i][i]%P;

	}

	return ret;

}

void dfs(int x,int f)

{

	if(x==n)

	{

		ans=(ans+f*calc())%P;

		return ;

	}

	S|=1<<(x-1),dfs(x+1,f);

	S^=1<<(x-1),dfs(x+1,-f);

}

int main()

{

	n=rd();

	int i,a;

	for(i=1;i<n;i++)

	{

		a=rd();

		while(a--)	pa[i].push_back(rd()),pb[i].push_back(rd());

	}

	dfs(1,1);

	ans=(ans+P)%P;

	printf("%lld",ans);

	return 0;

}