#include <cstdio>#include <cstring>#include <iostream>#include <algorithm>#include <vector>#include <set>#include <map>#include <cmath>#include <sstream>#include <iomanip>#include <queue>#include <ctime>using namespace std;template <class T> void checkmin(T &t,T x){if (x < t) t = x;}template <class T> void checkmax(T &t,T x){if (x > t) t = x;}template <class T> void _checkmin(T &t, T x){if (t == -1) t = x; if (x < t) t = x;}template <class T> void _checkmax(T &t, T x){if (t == -1) t = x; if (x > t) t = x;}typedef pair <int,int> PII;typedef pair <double,double> PDD;typedef long long lld;#define foreach(it,v) for (__typeof((v).begin()) it = (v).begin();it != (v).end();it++)#define DEBUG(a) cout << #a" = " << (a) << endl;#define DEBUGARR(a, n) for (int i = 0; i < (n); i++) { cout << #a"[" << i << "] = " << (a)[i] << endl; }#define maxn 100000#define oo 20000int f[maxn][3],son[maxn][4],trup[maxn];void calc(int now,int fa){ int L = -1,R = -1; if (trup[now]){ f[now][0] = oo,f[now][1] = 0; f[now][2] = 0; return ; } for (int i=1;i<=son[now][0];i++) if (son[now][i]!=fa){ if (L==-1) L = son[now][i]; else R = son[now][i]; calc(son[now][i],now); } if (L==-1){ f[now][0] =f[now][1] = 0; f[now][2] = 1; }else if (R==-1){ //one f[now][0] = f[L][0]; f[now][1] = f[L][1]; f[now][2] = f[L][2]; }else { f[now][0] = f[L][0]+f[R][0]; f[now][1] = min(f[L][0]+f[R][1],f[L][0]+f[R][2]); checkmin(f[now][1],min(f[R][0]+f[L][1],f[R][0]+f[L][2])); f[now][2] = min(f[now][1],f[now][0])+1; checkmin(f[now][2],f[L][2]+f[R][2]); }}int N,M; int main(){ int i,j,a; while(scanf("%d%d",&N,&M)){ if (N==0&&M==0) break; for (i=1;i<=N;i++){ scanf("%d",&son[i][0]); for (j=1;j<=son[i][0];j++) scanf("%d",&son[i][j]); trup[i] = 0; } for (i=0;i<M;i++) scanf("%d",&a),trup[a] = 1; calc(1,-1); printf("%dn",f[1][2]); }}
