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#include <bits/stdc++.h>
#define REP(a,b) for(int a=0; a<(b); ++a)
#define FWD(a,b,c) for(int a=(b); a<(c); ++a)
#define FWDS(a,b,c,d) for(int a=(b); a<(c); a+=d)
#define BCK(a,b,c) for(int a=(b); a>(c); --a)
#define ALL(a) (a).begin(), (a).end()
#define SIZE(a) ((int)(a).size())
#define SQ(a) ((a)*(a))
#define VAR(x) #x ": " << x << " "
#define popcount __builtin_popcount
#define popcountll __builtin_popcountll
#define gcd __gcd
#define x first
#define y second
#define st first
#define nd second
#define pb push_back

using namespace std;

template<typename T> ostream& operator<<(ostream &out, const vector<T> &v){ out << "{"; for(const T &a : v) out << a << ", "; out << "}"; return out; }
template<typename S, typename T> ostream& operator<<(ostream &out, const pair<S,T> &p){ out << "(" << p.st << ", " << p.nd << ")"; return out; }

typedef long long int64;
typedef pair<int, int> PII;
typedef pair<int64, int64> PLL;
typedef long double K;
typedef vector<int> VI;

const int dx[] = {0,0,-1,1}; //1,1,-1,1};
const int dy[] = {-1,1,0,0}; //1,-1,1,-1};

const int INF = 1000 * 1000 * 1000;

int n, m, res;
vector<int> nxt[510];
vector<int> target;
int ps[1010];
int trans[15][510][1010];

int when1[510];
int when2[510][510];

int cont(int k, int c){
	if(k == m) return k;
	while(k > 0 && c != target[k]) k = ps[k-1];
	if(c == target[k]) ++k;
	return k;
}

int main(){
	scanf("%d %d", &n, &m);
	FWD(i,1,n+1){
		int k;
		scanf("%d", &k);
		FWD(j,0,k){
			int a;
			scanf("%d", &a);
			nxt[i].push_back(a);
		}
	}
	FWD(i,0,m){
		int a;
		scanf("%d", &a);
		target.push_back(a);
	}
	FWD(i,1,m){
		ps[i] = ps[i-1];
		while(ps[i] > 0 && target[i] != target[ps[i]]) ps[i] = ps[ps[i]-1];
		if(target[i] == target[ps[i]]) ps[i]++;
	}

	FWD(i,1,n+1){
		FWD(k,0,m+1){
			trans[0][i][k] = cont(k, i);
		}
	}

	FWD(r,1,15){
		FWD(i,1,n+1){
			FWD(k,0,m+1){
				int s = k;
				for(int u : nxt[i]) s = trans[r-1][u][s];
				trans[r][i][k] = s;
			}
		}
	}
	
	res = INF;

	FWD(i,1,n+1) when1[i] = INF;
	priority_queue<PII> Q;
	Q.push(PII(-1,1));
	while(!Q.empty()){
		int u = Q.top().nd;
		int d = -Q.top().st;
		Q.pop();
		if(when1[u] != INF) continue;
		when1[u] = d;
		for(int v : nxt[u])
			Q.push(PII(-d-1, v));
	}

	FWD(t,0,15)
		FWD(i,1,n+1)
			if(trans[t][i][0] == m){
				//printf("%d %d %d\n", t, i, when1[i]);
				res = min(res, when1[i]+t);
			}

	FWD(i,1,n+1) FWD(j,1,n+1) when2[i][j] = INF;
	priority_queue<pair<int, PII>> R;
	FWD(i,1,n+1){
		if(when1[i] == INF) continue;
		FWD(j,0,SIZE(nxt[i])-1)
			R.push(make_pair(-when1[i]-1, PII(nxt[i][j], nxt[i][j+1])));
	}
	while(!R.empty()){
		int d = -R.top().st;
		int u = R.top().nd.st;
		int v = R.top().nd.nd;
		R.pop();
		if(when2[u][v] != INF) continue;
		when2[u][v] = d;
		R.push(make_pair(-d-1, PII(nxt[u].back(), nxt[v].front())));
	}

	FWD(t,0,15)
		FWD(i,1,n+1)
			FWD(j,1,n+1)
				if(trans[t][j][trans[t][i][0]] == m){
					res = min(res, when2[i][j]+t);
				}

	if(res == INF) res = -1;
	printf("%d\n", res);
	return 0;
}