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#include<cstdio>
#include<algorithm>
#include<utility>
#include<string>
#include<vector>
#include<map>
#include<set>
#include<queue>
#include<stack>
#include<cmath>
#include<iostream>

#define FORE(c, a, b) for(int c=a; c<= int(b); ++c)
#define FORD(c, a, b) for(int c=a; c>= int(b); --c)
#define FORIT(it, cont, cont_t) for(cont_t::iterator it = cont.begin(); it != cont.end(); ++it)
#define REP(i, n) for(int i = 0; i < (n); ++i)
#define ALL(a) a.begin(), a.end() 
#define PR(n) printf("%d ", (int) (n)) 
#define PRL(n) printf("%lld ", (ll) (n)) 
#define SC(n) scanf("%d ", &n) 

#define xx first
#define yy second
#define pb push_back
#define mp make_pair
#define itr iterator

#define dbg if(0)
#define prd dbg printf

using namespace std;

typedef long long ll;
typedef long double ld;
typedef unsigned int uint;

typedef vector<int> vi;
typedef set<int> si;
typedef map<int, int> mi;
typedef pair<int, int> pi;
typedef vector<pi> vii;
typedef vector<vi> vvi;

const int NMAX = 1009, TEN = 11;
const int LEFT = 0, RIGHT = 1;
const int HH = 2;
int hashQ[HH] = {1000003351, 1000008041};
int hashP[HH] = {2801, 3002231};
int hashR[HH] = {531597640, 455940268};

int n, m, x, k;
int farLeft[NMAX][TEN], farRight[NMAX][TEN], computed[NMAX], f[NMAX];
int res[NMAX][NMAX], vis[NMAX][NMAX];
vi hash1[HH], hash2[HH], hashSeq[HH];
vi prod[NMAX];
vi adult, suf1, suf2;

void add_(int &x, int y, int &j) {
	x += y;
	x = x >= hashQ[j] ? x - hashQ[j] : x;
}

void mult_(int &x, int y, int &j) {
	x = ((ll) x * y) % hashQ[j];
}

vi unFold(vi & seq, int dir) {
	vi ans;
	if(dir == LEFT) {
		FORE(i, 0, seq.size() - 1) {
			int sym = seq[i];
			ans.insert(ans.end(), ALL(prod[sym]));
			if(ans.size() > m) {
				ans.pb(n);
				return ans;
			}
		}
	} else { // RIGHT
		FORD(i, seq.size() - 1, 0) {
			int sym = seq[i];
			vi tmp = prod[sym];
			reverse(ALL(tmp));
			ans.insert(ans.end(), ALL(tmp));
			if(ans.size() > m) {
				ans.pb(n);
				reverse(ALL(ans));
				return ans;
			}
		}
	}
	if(dir == RIGHT)
		reverse(ALL(ans));
	return ans;
}

vi computeKMP(vi &s) {
	prd("kmp\n");
    vi ans(s.size());
    int j = ans[0] = 0;
    for (int i = 1; i < s.size(); i++) {
        while (j > 0 && s[j] != s[i])
            j = ans[j-1];
        if (s[j] == s[i])
            j++;
        ans[i] = j;
        prd("%d: %d\n", i, ans[i]);
    }   
    return ans;
}

vi computeHash(vi &s, int ha) {
	int hash = 0, x = 1;
	vi ans(s.size());
	
	REP(i, s.size()) {
		int a = s[i] + 1;
		mult_(a, x, ha);
		mult_(x, hashP[ha], ha);
		add_(hash, a, ha);
		ans[i] = hash;
		//prd("%d: %d\n", i, ans[i]);
	}
	return ans;
}

vi computeReverseHash(vi &hash, int ha) {
	int x = 1;
	vi ans(hash.size());
	
	REP(i, hash.size()) {
		int a = hash.back();
		add_(a, hashQ[ha] - (i ? hash[i-1] : 0), ha);
		mult_(a, x, ha);
		mult_(x, hashR[ha], ha);
		ans[i] = a;
	}
	return ans;
}

int hashesOk(vi h1[], vi h2[], int pos1, int pos2) {
	REP(ha, HH) {
		prd("hashes %d: %d, %d: %d\n", pos1, h1[ha][pos1], pos2, h2[ha][pos2]);
		if(h1[ha][pos1] != h2[ha][pos2])
			return 0;
	}
	return 1;
}

/*void extendedGcd(int a, int b) {
    s = 0; old_s = 1;
    t = 1; old_t = 0;
    r = b; old_r := a;
    while (r!=0) {
        int quotient = old_r / r;
        //(old_r, r) := (r, old_r - quotient * r)
        tmp = r; r = old_r - quotient * r; old_r = r;
        //(old_s, s) := (s, old_s - quotient * s)
        tmp = s; s = old_s - quotient * s; old_s = tmp;
        //(old_t, t) := (t, old_t - quotient * t)
        tmp = t; t = old_t - quotient * t; old_t = tmp;
    }
    //output "Bézout coefficients:", (old_s, old_t)
    //output "greatest common divisor:", old_r
    //output "quotients by the gcd:", (t, s)
}*/

int superWord(int xa, int xb) { // TODO check indeksy
	if(xa + xb < m)
		return 0;
	int oa = xa ? (xa - suf2[m - xa]) : 0, ob = xb ? (xb - suf1[xb - 1]) : 0;
	int len = xa + xb - m;
	
	// czy istnieja ya * oa + yb * ob = len ?
	if(oa == 0 && ob == 0)
		return len == 0;
	if(oa == 0)
		return (len % ob == 0);
	if(ob == 0)
		return (len % oa == 0);
		
	/*extendedGcd(oa, ob);
	int gcd = old_r, ia = old_s, ib = old_t;
	if(len % gcd != 0) return 0;*/
	
	while((len % ob != 0) && len >= 0)
		len -=  oa; 
	return len >= 0;
}

void dfs(int s1, int s2) {
	vis[s1][s2] = 1;
	int t1 = prod[s1].back();
	int t2 = prod[s2][0];
	if(!vis[t1][t2] && res[t1][t2] == NMAX * NMAX)
		dfs(t1, t2);
	res[s1][s2] = 1 + res[t1][t2];
}

int getFarLeft(vi & seqq) {
	int ans = 0;
	REP(ha, HH)
		hashSeq[ha] = computeHash(seqq, ha);
	for(int i = 0; i < m && i < seqq.size(); i++)
		if(hashesOk(hash2, hashSeq, m - i - 1, i))
			ans = i + 1;
	return ans;
}
int getFarRight(vi & seqq) {
	int ans = 0;
	REP(ha, HH) {
		vi tmp = computeHash(seqq, ha);
			hashSeq[ha] = computeReverseHash(tmp, ha);
		}
	for(int i = 0; i < m && i < seqq.size(); i++)
		if(hashesOk(hash1, hashSeq, i, seqq.size() - 1 - i))
			ans = i + 1;
	return ans;
}

void compute(int sym) {
	prd("compute %d\n", sym);
	computed[sym] = 1;
	if(m == 1 && adult[0] == sym) {
		f[sym] = 1; return;
	}
	
	int pp = prod[sym].size();
	REP(pi, pp) {
		int s0 = prod[sym][pi];
		if(!computed[s0])
			compute(s0);
		f[sym] = min(f[sym], f[s0] + 1);
	}
	prd("status %d\n", f[sym]);
	
	REP(pi, pp-1) {
		int s1 = prod[sym][pi], s2 = prod[sym][pi+1];
		f[sym] = min(f[sym], res[s1][s2] + 2);
	}
	prd("status %d\n", f[sym]);
	
	REP(pi, pp-1) {
		int s1 = prod[sym][pi], s2 = prod[sym][pi+1];
		vi::itr secStart = prod[sym].begin() + pi + 1;
		
		vi prod1(prod[sym].begin(), secStart);
		vi prod2(secStart, prod[sym].end());
		
		REP(di, TEN) {
			int farRight0 = getFarRight(prod1);
			int farLeft0 = getFarLeft(prod2);
			
			if(superWord(farRight0, farLeft0)) {
				prd("found unfolded di %d pi %d\n", di, pi);
				f[sym] = min(f[sym], di + 2);
			}
			prod1 = unFold(prod1, RIGHT);
			prod2 = unFold(prod2, LEFT);
		}
	}
	prd("f[%d] = %d\n", sym, f[sym]);
}		

int main() {
	scanf("%d%d\n", &n, &m);
	REP(i, n) {
		scanf("%d", &k);
		REP(j, k) {
			scanf("%d", &x);
			prod[i].pb(x-1);
		}
		f[i] = NMAX * NMAX;
	}
	prod[n].pb(n);
	REP(i, m) {
		scanf("%d", &x);
		adult.pb(x-1);
	}
	
	// ------- 1
	vi adultRev(adult); reverse(ALL(adultRev));
	suf1 = computeKMP(adult);
	suf2 = computeKMP(adultRev);
	reverse(ALL(suf2));
	
	REP(ha, HH) {
		hash1[ha] = computeHash(adult, ha);
		hash2[ha] = computeReverseHash(hash1[ha], ha);
	}
	
	// ------- 2
	REP(sym, n) {
		prd("symbol %d\n", sym);
		vi seq; seq.pb(sym);
		REP(di, TEN) {
			farLeft[sym][di] = getFarLeft(seq);
			seq = unFold(seq, LEFT);
						
			prd("unfolded left %d:\n", di);
			dbg FORIT(it, seq, vi) printf("%d ", *it);
			prd("farLeft %d \n", farLeft[sym][di]);
		}
		
		seq.clear(); seq.pb(sym);
		REP(di, TEN) {
			farRight[sym][di] = getFarRight(seq);
			seq = unFold(seq, RIGHT);
			
			prd("unfolded right %d:\n", di);
			dbg FORIT(it, seq, vi) printf("%d ", *it);
			prd("farRight %d \n", farRight[sym][di]);
		}
	}
	
	// ------- 3
	REP(sym1, n) REP(sym2, n) {
		res[sym1][sym2] = NMAX * NMAX;
		FORD(di, TEN-1, 0)
			if(superWord(farRight[sym1][di], farLeft[sym2][di]))
				res[sym1][sym2] = di;
	}
	dbg REP(i, m+1) REP(j, m+1)
		if(superWord(i, j))
			printf("superWord %d %d\n", i, j);
	
	// ------- 4
	REP(sym1, n) REP(sym2, n) {
		if(!vis[sym1][sym2] && res[sym1][sym2] == NMAX * NMAX)
			dfs(sym1, sym2);
		prd("res %d %d = %d\n", sym1, sym2, res[sym1][sym2]);
	}
	
	compute(0);
	printf("%d\n", f[0] >= NMAX * NMAX ? -1 : f[0]);
	return 0;
}