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#include <cstdio>
//#include <iostream>
//#include <algorithm>
//#include <string>
#include <vector>
//#include <complex>
//#include <iterator>
//#include <set>
//#include <bitset>
//#include <map>
//#include <stack>
//#include <list>
//#include <queue>
//#include <deque>
using namespace std;
typedef vector<int> VI;
typedef long long LL;
#define FOR(x, b, e) for(int x = b; x <= (e); ++x)
#define FORD(x, b, e) for(int x = b; x >= (e); --x)
#define REP(x, n) for(int x = 0; x < (n); ++x)
#define VAR(v, n) typeof(n) v = (n)
#define ALL(c) (c).begin(), (c).end()
#define SIZE(x) ((int)(x).size())
#define FOREACH(i, c) for(VAR(i, (c).begin()); i !=(c).end(); ++i)
#define FORE(i, c) for(VAR(i, (c).begin()), KS=(c).end(); i !=KS; ++i)
#define PB push_back
#define ST first
#define ND second
const int INF = 1000000001;
const double EPS = 10e-9;
typedef vector<VI> VVI;
typedef vector<LL> VLL;
typedef vector<double> VD;
//typedef vector<string> VS;
typedef pair<int, int> PII;
typedef vector<PII> VPII;
#define PF push_front
#define MP make_pair
struct tri
{
  int a,b,c;
  tri(int k=0,int l=0,int m=0)
  {
    a=k;
    b=l;
    c=m;
  }
};
int l=1;
 void KMP(const VI& str,const VI& wzo) {
 #define KMPH(z) while(k > 0 && wzo[k] != z[q]) k = p[k]; if(wzo[k] == z[q]) k++;
 int k = 0, q, m;
 VI p(wzo.size()+1);
 p[1] = 0;
 for (q = 1; q<SIZE(wzo); q++) {
   KMPH(wzo);
   p[q + 1] = k;
 }
  m = q;
  k = 0;
  for (q = 0; q<SIZE(str); q++) {
    KMPH(str);
    if(m == k) {
      printf("%d\n",l);
      l=-1;
      return;
      k = p[k];
   }
 }
}
void krok(VI& z,VI& d,VVI& ew)
{
  d.clear();
  int i,j,k=0;
  for(i=0;i<SIZE(z);++i)
    k+=SIZE(ew[z[i]]);
  if(k>3000000)
  {
    printf("-1\n");
    l=-1;
    return;
  }
  for(i=0;i<SIZE(z);++i)
    for(j=0;j<SIZE(ew[z[i]]);++j)
      d.PB(ew[z[i]][j]);
}
int main()
{
  int n,m,b,i,j;
  scanf("%d%d",&n,&m);
  VVI ew(n+1);
  VI d(m),p(1,1),q;
  for(i=1;i<=n;++i)
  {
    scanf("%d",&b);
    ew[i].resize(b);
    for(j=0;j<b;++j)
    {
      scanf("%d",&ew[i][j]);
    }
  }
  for(i=0;i<m;++i)
    scanf("%d",&d[i]);
  while(~l)
  {
    KMP(p,d);
    if(l==-1)
      return 0;
    ++l;
    krok(p,q,ew);
    if(l==-1)
      return 0;
    KMP(q,d);
    if(l==-1)
      return 0;
    ++l;
    krok(q,p,ew);
  }
  return 0;
}