#include<cstdio>

#include<cstring>

using namespace std;

const int maxn=;

int n,m;

struct edge{

    int from,to,money;

    int next;

}e[maxn*];

int read()

{

    int x=,f=;char c=getchar();

    while(!isdigit(c)){if(c=='-')f=-;c=getchar();}

    while(isdigit(c)){x=x*+c-'';c=getchar();}

    return x*f;

}

int cnt=,head[maxn];

int f1[maxn][maxn],f2[maxn][maxn];

int corn[maxn];

int sum;

void edge(int x,int y,int c)

{

    e[cnt].from=x;

    e[cnt].to=y;

    e[cnt].money=c;

    e[cnt].next=head[x];

    head[x]=cnt++;

}

void tree_dp(int i)

{

    if(i<=n-m)

    for (int j=head[u];!j;j=e[j].next)

    {

        tree_dp(e[i].to);

    }

    else {

    }

}

void work()

{

    n=read(),m=read();

    for(int i=;i<=n-m;i++)

    {

        int q,w;

        q=read();

        for(int j=;j<=q;j++)

        {

            int a,b;

            a=read(),b=read();

            addedge(i,a,b);

            addedge(a,i,b);

        }

    }

    for (int i=;i<=m;i++)

    scanf("%d",c[i]),sum+=c[i];

    tree_dp();

    printf("%d",ans);

}

int main()

{

    work();

    return ;

}