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#include <bits/stdc++.h>

#define FOR(i,a,b) for(int i=(a);i<(b);++i)
#define FORD(i, a, b) for(int i = (a); i >= (b); --i)
#define VAR(v, i) __typeof(i) v=(i)
#define FORE(i, c) for(VAR(i, (c).begin()); i != (c).end(); ++i)
#define all(v) (v).begin(),(v).end()

#define VI vector<int>
#define PII pair<int,int>
#define st first
#define nd second
#define mp make_pair
#define pb push_back
#define lint long long int

#define debug(x) {cerr <<#x <<" = " <<x <<endl; }
#define debug2(x,y) {cerr <<#x <<" = " <<x << ", "<<#y<<" = "<< y <<endl; } 
#define debug3(x,y,z) {cerr <<#x <<" = " <<x << ", "<<#y<<" = "<< y << ", " << #z << " = " << z <<endl; } 
#define debugv(x) {{cerr <<#x <<" = "; FORE(itt, (x)) cerr <<*itt <<", "; cerr <<endl; }}
#define debugt(t,n) {{cerr <<#t <<" = "; FOR(it,0,(n)) cerr <<t[it] <<", "; cerr <<endl; }}

#define make( x) int (x); scanf("%d",&(x));
#define make2( x, y) int (x), (y); scanf("%d%d",&(x),&(y));
#define make3(x, y, z) int (x), (y), (z); scanf("%d%d%d",&(x),&(y),&(z));
#define make4(x, y, z, t) int (x), (y), (z), (t); scanf("%d%d%d%d",&(x),&(y),&(z),&(t));
#define makev(v,n) VI (v); FOR(i,0,(n)) { make(a); (v).pb(a);} 
#define IOS ios_base::sync_with_stdio(0)
#define HEAP priority_queue

#define read( x) scanf("%d",&(x));
#define read2( x, y) scanf("%d%d",&(x),&(y));
#define read3(x, y, z) scanf("%d%d%d",&(x),&(y),&(z));
#define read4(x, y, z, t) scanf("%d%d%d%d",&(x),&(y),&(z),&(t));
#define readv(v,n) FOR(i,0,(n)) { make(a); (v).pb(a);}

using namespace std;

int n,m;
VI S;
VI rep[505];

int start[505];
int start_pary[505][505];

void wypelnij() {
  FOR(i,1,n+1) start[i] = -1;
  FOR(i,1,n+1) FOR(j,1,n+1) start_pary[i][j] = -1;
  VI kolejka;
  kolejka.pb(1); start[1] = 1;
  int pocz = 0;
  while (pocz < kolejka.size()) {
    int a = kolejka[pocz]; pocz++;
    FOR(i,0,rep[a].size()) {
      int w = rep[a][i];
      if (start[w] == -1) {
        start[w] = start[a]+1;
        kolejka.pb(w);
      }
    }
  }
  vector<PII> kolejka2;
  FOR(i,0,rep[1].size()-1) {
    kolejka2.pb(mp(rep[1][i], rep[1][i+1]));
    start_pary[rep[1][i]][rep[1][i+1]] = 2;
  }
  pocz = 0;
  while (pocz < kolejka2.size()) {
    int a = kolejka2[pocz].st, b = kolejka2[pocz].nd; pocz++;
    FOR(i,0,rep[a].size()-1) {
      int u = rep[a][i], v =rep[a][i+1];
      if (start_pary[u][v] == -1) {
        start_pary[u][v] = start_pary[a][b]+1;
        kolejka2.pb(mp(u,v));
      }
    }
    FOR(i,0,rep[b].size()-1) {
      int u = rep[b][i], v =rep[b][i+1];
      if (start_pary[u][v] == -1) {
        start_pary[u][v] = start_pary[a][b]+1;
        kolejka2.pb(mp(u,v));
      }
    }
    int u = rep[a].back(), v = rep[b][0];
    if (start_pary[u][v] == -1) {
        start_pary[u][v] = start_pary[a][b]+1;
        kolejka2.pb(mp(u,v));
    }
  }
}

int p = 521;
int mod = 1070000027;

VI pref[505][13];
VI hashe_pref[505][13];

VI suf[505][13];
VI hashe_suf[505][13];
int przekracza[505];

int hashS[1005][1005];

void przeklej_przod(VI& v1, VI& v2, int ile) {
  FOR(i,0,ile) v2.pb(v1[i]);
}

void przeklej_tyl(VI& v1, VI& v2, int ile) {
  FOR(i,0,ile) v2.pb(v1[v1.size()-ile+i]);
}

void generuj() {
  FOR(i,1,n+1){
    VI v; v.pb(i);
    pref[i][0] = v;
  } 
  FOR(j,1,13) {
    FOR(i,1,n+1) {
      int hp_dl = 0;
      FORE(k,pref[i][j-1]) {
        int jeszcze = min( (int) rep[*k].size(), (m+1)-hp_dl);
        if (jeszcze == 0) break;
        przeklej_przod(rep[*k],pref[i][j], jeszcze);
        hp_dl += jeszcze;
      }
    }
  }
  FOR(i,1,n+1){
    FOR(j,0,13) {
      if(pref[i][j].size()>m){
        przekracza[i] = j;
        break;
      }
    }
  }
  
  FOR(j,0,13) {
    FOR(i,1,n+1) {
      if(pref[i][j].size() < m+1) suf[i][j] = pref[i][j];
      else {
        int hp_dl = 0;
        int k = suf[i][j-1].size();
        while (hp_dl < m+1) {  
          k--;
          int literka = suf[i][j-1][k];
          hp_dl += rep[literka].size(); 
        }
      //  debug2(k,hp_dl);
      //  debug(suf[i][j-1][k]);
        przeklej_tyl(rep[suf[i][j-1][k]], suf[i][j], rep[suf[i][j-1][k]].size()-(hp_dl-(m+1)));
        k++;
        FOR(u,k,suf[i][j-1].size()) {
          int literka = suf[i][j-1][u];
          przeklej_tyl(rep[suf[i][j-1][u]], suf[i][j], rep[suf[i][j-1][u]].size());
        }
        //debug2(i,j);
        //debugv(suf[i][j]);
      }
    }
  }
}

map<int, VI> hasher[1005]; // hashe[i] , dla hasha podsłów długości i zwraca liste poczatkow 

void licz_hashe() {
  FOR(i,1,n+1) {
    FOR(j,0,13) {
      int hash = 0;
      FOR(u,0,pref[i][j].size()) {
        hash = (hash*1LL*p)%mod;
        hash += pref[i][j][u];
        if (hash >= mod) hash-=mod;
        hashe_pref[i][j].pb(hash);
      }
    }
  }
  
  FOR(i,1,n+1) {
    FOR(j,0,13) {
      int hash = 0;
      int potega = 1;
      FORD(u,suf[i][j].size()-1,0) {
        hash += (potega*1LL*suf[i][j][u])%mod;
        if (hash>= mod) hash-=mod;
        hashe_suf[i][j].pb(hash);
        potega = (potega*1LL*p)%mod;
      }
    }
  }

  FOR(i,0,m) hashS[i][i] = S[i];
  FOR(d,1,m) {
    FOR(i,0,m-d) {
      hashS[i][i+d] = (hashS[i][i+d-1]*1LL*p)%mod;
      hashS[i][i+d] += S[i+d];
      if (hashS[i][i+d] >= mod) hashS[i][i+d] -= mod;
    }
  }
  FOR(d,0,m) {
    FOR(i,0,m-d) {
      if(hasher[d].find(hashS[i][i+d])!=hasher[d].end()) {
        hasher[d][hashS[i][i+d]].pb(i);
      } else {
        VI w; w.pb(i);
        hasher[d][hashS[i][i+d]] = w;
      }
    }
  }
  
//  FOR(i,0,m) debugt(hashS[i],m);
}




int best = 1e9;

int zJednego(int k) {
  if( rep[k].size() >= m ) {
    FOR(i,0,rep[k].size()-m+1){
      bool ok = true;
      FOR(j,0,m) {
        if(rep[k][i+j]!=S[j]) {
          ok = false;
          break;
        }
      }
      if(ok) return 1;
    }
  }
  int ans = 1e9;
  int co_najmniej_krok = przekracza[k];
  if(co_najmniej_krok >= 1 && pref[k][co_najmniej_krok-1].size() ==m) co_najmniej_krok--;
  FOR(i,1,rep[k].size()-1) {
    int loc_res = 0;
    int l = rep[k][i];
    FOR (step, co_najmniej_krok-1, przekracza[l]) {
      if(ans < step || best < step) break;
      
      int dlugosc_srodka = pref[l][step].size();
      int H = hashe_pref[l][step].back();
      if (hasher[dlugosc_srodka-1].find(H) != hasher[dlugosc_srodka-1].end()) {
        FORE(j, hasher[dlugosc_srodka-1][H]) {
          int pocz = *j; if(pocz==0) continue;
          if (hashe_suf[rep[k][i-1]][step][pocz-1] == hashS[0][pocz-1]) {
            
            int start = pocz+dlugosc_srodka;
            bool okk = true;
            int psi = i+1;
            while (1) {
              if( psi >= rep[k].size() ) {
                okk = false;
                break;
              }
              if (pref[rep[k][psi]][step].size() >= m-start) {
                if(hashe_pref[rep[k][psi]][step][m-start-1] != hashS[start][m-1]) {
                  okk = false;
                }
                break;
              } else {
                if(hashe_pref[rep[k][psi]][step].back() != hashS[start][start+pref[rep[k][psi]][step].size()-1]) {
                  okk = false;
                  break;
                } else {
                  start += pref[rep[k][psi]][step].size();
                  psi++;
                }
              }
            }
            if(okk) { 
              ans = min(ans, step);
            }
          }
        }
      }
    }
  }
  return ans+1;
}

VI pref_pas[505][13];
VI suf_pas[505][13];

void przygotuj_pary() {
  FOR(i,1,n+1) FOR(j,0,13) 
  FOR(u,0,min((int) pref[i][j].size(),m)) {
    if(hashe_pref[i][j][u] == hashS[m-1-u][m-1]) pref_pas[i][j].pb(u);
  }
  FOR(i,1,n+1) FOR(j,0,13) {
    FOR(u,0,min((int) suf[i][j].size(),m)) {
      if(hashe_suf[i][j][u] == hashS[0][u]) suf_pas[i][j].pb(u);
    }
  }
}

bool jest(VI& v, int k) {
  if(v.size()==0) return false;
  int lewo = 0, prawo = v.size()-1;
  while (prawo-lewo > 1) {
    int sr = (prawo+lewo)/2;
    if (v[sr] > k) prawo = sr;
    else lewo = sr;
  }
  if(v[lewo]==k) return true;
  if(v[prawo]==k) return true;
  return false;
}

int zPary(int k,int l) {
   
  FOR(step,1,13) {
    if (suf[k][step].size() + pref[l][step].size()<m) continue;
    FORE(j,suf_pas[k][step]) {
      int ile = *j+1;
      int reszta = m-ile-1;
      if (jest(pref_pas[l][step],reszta)) return step;
    }
  }
  return 1e9;
}
  
int main(){
  read2(n,m);
  FOR(j,1,n+1) {
    make(a);
    rep[j].clear();
    FOR(i,0,a) {
      make(b); rep[j].pb(b);
    }
  }
  readv(S,m);
  wypelnij();
  //cout<<"WYPELNIL"<<endl;
  if (m==1) {
    printf("%d\n",start[S[0]]);
    return 0;
  } 
  if (m==2) {
    printf("%d\n",start_pary[S[0]][S[1]]);
    return 0;
  }
  generuj();
  //cout<<"WYGENEROWAL"<<endl;
  licz_hashe();
  przygotuj_pary();
  FOR(i,1,n+1) {
    //debug3(i,start[i], zJednego(i));
    if(start[i]!=-1) best = min(best, zJednego(i)+start[i]);
  }
  FOR(i,1,n+1) FOR(j,1,n+1) {
    if(start_pary[i][j]!=-1) best = min(best, zPary(i,j)+start_pary[i][j]);
  }
  if(best==1e9) {
    printf("-1\n");
  } else {
    printf("%d\n",best);
  }
}