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#include<bits/stdc++.h>
#define PII pair<int,int>
#define f first
#define s second
#define VI vector<int>
#define LL long long
#define MP make_pair
#define LD long double
#define PB push_back
#define ALL(V) V.begin(),V.end()
#define abs(x) max((x),-(x))
#define PDD pair<LD,LD> 
#define VPII vector< PII > 
#define siz(V) ((int)V.size())
#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 mini(a,b) a=min(a,b)
#define maxi(a,b) a=max(a,b)
using namespace std;
int n,a,b,c,d,k,m,q,z;
const int MXN=505;
int WYW;
VI wzor;
LL hwzor;
int R(int a,int b)
	{
	return rand()%(b-a+1)+a;
	}
VI V[MXN];
void operator+=(VI &a,VI b)
	{
	REP(i,b.size())
		{
		a.PB(b[i]);
		}
	}
VI next(VI c)
	{
	VI c2;
	REP(i,c.size())
		{
		c2+=V[c[i]];
		}
	return c2;
	}

const LL MOD=(1<<17)-1;//chyba optymalne dla 10^6 elementów, ew 16
struct mapa
{
int SIZ=0;
vector<pair<LL,int> > V[MOD+1];
inline int &operator[](LL a)
  {
  int x=a&MOD;
  for(int i=0;i<V[x].size();i++)
    {
    if(V[x][i].first==a)return V[x][i].second;
    }
  SIZ++;
  V[x].push_back(make_pair(a,0));

  return V[x].back().second;
  }
inline bool count(LL a)
  {
  int x=a&MOD;
  for(int i=0;i<V[x].size();i++)
    {
    if(V[x][i].f==a)return 1;
    }
  return 0;
  }
}S;

queue<VI> Q;
int l=1013;
LL L=1000000000001371;
LL ldom=1;
LL hasz(VI V)
	{
	LL ret=0;
	REP(i,V.size())
		{
		ret=(ret*l+V[i])%L;
		}	
	return ret;
	}
void look(VI V,int lvl)
	{
//	WYW++;
//	if(S.count(hasz(V)))return;
	LL hV=hasz(V);
//	cerr<<"V: "<<V.size()<<" z: ";REP(i,V.size())cerr<<V[i]<<" ";cerr<<endl;
//	cerr<<hV<<endl;
	if(hV==hwzor)
		{
		printf("%d\n",lvl+1);
		exit(0);
		}
	S[hV]=lvl+1;
	Q.push(V);
	}
VI tovec(VI &V,int a,int b)
	{
	VI ret;
	FOR(i,a,b)
		ret.PB(V[i]);
	return ret;
	}
void wrzucaj(VI V,int lvl)
	{
	if(V.size()<m)
		{
		if(S.count(hasz(V))==0)
			look(V,lvl);
		return;
		}
	LL h=hasz(tovec(V,0,m-1));
	if(S.count(h)==0)
		look(tovec(V,0,m-1),lvl);
	FOR(i,m,(int)V.size()-1)
		{
		h*=l;
		h+=V[i];
		h-=ldom*V[i-m];
		h+=L*1000LL;
		h%=L;
		if(S.count(h))continue;
		look(tovec(V,i-m+1,i),lvl);
		}
	}
void reg(VI V)
	{
	Q.push(V);
	S[hasz(V)]=1;
	while(Q.size())
		{
		V=Q.front();
		Q.pop();
		LL hV=hasz(V);
		int lvl=S[hV];
//		cerr<<lvl<<" r"<<endl;
//	  cerr<<"V:: ";REP(i,V.size())cerr<<V[i]<<" ";cerr<<endl;
		V=next(V);
		wrzucaj(V,lvl);
		}
	}
void go()
	{
	scanf("%d%d",&n,&m);
	REP(i,m)ldom=ldom*l%L;
	FOR(i,1,n)
		{
		int w;
		scanf("%d",&w);
		REP(j,w)
			{
			scanf("%d",&a);
			V[i].PB(a);
			}
		}
	REP(i,m)
		{
		scanf("%d",&a);
		wzor.PB(a);
		}
	if(wzor.size()==1&&wzor[0]==1)
		{
		puts("1");
		return;
		}
	hwzor=hasz(wzor);
	VI c={1};
	reg(c);
	puts("-1");return;
/*	cerr<<"MXLVL: "<<mxl<<endl;
	printf("S.size: %d\n",S.SIZ);
	cerr<<"WYW: "<<WYW<<endl;
	return;
	*/
	}
main()
{
go();
}