#include
#include<string>
#include
using namespace std;
const int MAXN = 3e3+10;
int cost[MAXN];
int dp[MAXN][MAXN];
struct Edge{
int v, next, w;
}edge[MAXN];
int head[MAXN];
int cnt;
void addEdge(int u, int v, int w){
edge[cnt].v = v;
edge[cnt].next = head[u];
edge[cnt].w = w;
head[u] = cnt++;
return;
}
void ini(int n, int m)
{
for(int i = 1; i <= n; i++)
head[i] = -1;
cnt = 0;
// for(int i = 1; i <= n; i++)
// {
// for(int z = 1; z <= m; z++)
// dp[i][z] = -1;
// }
memset(dp, ~0x3f, sizeof(dp));
for(int i = 1; i <= n; i++)
dp[i][0] = 0;
return;
}
int dfs(int u)
{
int sum;
if(cost[u])
sum = 1;
else
sum = 0;
int temp;
for(int i = head[u]; ~i; i = edge[i].next)
{
int v = edge[i].v;
temp = dfs(v); sum +=temp;
for(int z = sum; z >= 1; z--)
{
for(int j = 1; j <= z&& j <= temp; j++)
{
dp[u][z] = max(dp[u][z], dp[u][z-j]+dp[v][j]-edge[i].w);
}
}
}
return sum;
}
int main()
{
int n, m;
cin >> n >> m;
ini(n, m);
int num1 = n-m;
for(int i = 1; i <= num1; i++)
{
int num2, v, w;
cin >> num2;
for(int z = 1; z <= num2; z++)
{
cin >> v >> w;
addEdge(i, v, w);
}
}
for(int i = n-m+1; i <= n; i++)
{
cin >> cost[i];
dp[i][1] = cost[i];
}
dfs(1);
int ans = 0;
for(int i = 1; i <= m; i++)
{
if(dp[1][i] >= 0) ans = i;
}
cout << ans;
return 0;
}