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#include<iostream>
#include<cstdio>
#include<vector>
using namespace std;

int drzewo[1001][500];
vector<int> index[1001];
vector<int> index2[10001];
vector<int> index3[1001];
vector<int> index4[10001];
int drzewo2[10001][500];
int v2[1000];
vector<pair<int, int> > wektor[2][1001];
int it_wek=1;
bool DONE;
int m;
short bits[1000];

bool krok(int start, int ver_i, int ver_v){
    bool b=false;
    //cout<<start<<" "<<ver_i<<" "<<ver_v<<endl;
    if(ver_v==m){
        b=true;
        if(start){
            for(int i=0;i<index3[ver_i].size();i++){
                wektor[it_wek%2][start].push_back(make_pair(index3[ver_i][i],m));
                b=true;
            }
        }else{
            for(int i=0;i<index4[ver_i].size();i++){
                wektor[it_wek%2][start].push_back(make_pair(index4[ver_i][i],m));
                if(index4[ver_i][i]==0){
                    DONE=true;
                    return false;
                }
            }
        }
        return true;
    }
    if(start==0){
        for(int i=0;i<wektor[(it_wek-1)%2][ver_v].size();i++){
            //cout<<"TUTAJ JESTEM "<<wektor[it_wek-1][ver_v][i].first<<" "<<drzewo2[ver_i][wektor[it_wek-1][ver_v][i].first]<<endl;
            if(drzewo2[ver_i][wektor[(it_wek-1)%2][ver_v][i].first]){
                b=krok(start,drzewo2[ver_i][wektor[(it_wek-1)%2][ver_v][i].first],wektor[(it_wek-1)%2][ver_v][i].second)||b;
            }
        }
        if(index2[ver_i].size()){
            if(bits[ver_v]==1){
                b=true;
                for(int i=0;i<index2[ver_i].size();i++){
                    wektor[it_wek%2][start].push_back(make_pair(index2[ver_i][i],ver_v));
                }
            }else if(bits[ver_v]==0){
                if(krok(ver_v,0,ver_v)){
                    bits[ver_v]=1;
                    b=true;
                    for(int i=0;i<index2[ver_i].size();i++){
                        wektor[it_wek%2][start].push_back(make_pair(index2[ver_i][i],ver_v));
                    }
                }else{
                    bits[ver_v]=2;
                }
            }
        }
    }else{
        if(index[ver_i].size()){
            if(bits[ver_v]==1){
                b=true;
                for(int i=0;i<index[ver_i].size();i++){
                    wektor[it_wek%2][start].push_back(make_pair(index[ver_i][i],ver_v));
                }
            }else if(bits[ver_v]==0){
                if(krok(ver_v,0,ver_v)){
                    bits[ver_v]=1;
                    b=true;
                    for(int i=0;i<index[ver_i].size();i++){
                        wektor[it_wek%2][start].push_back(make_pair(index[ver_i][i],ver_v));
                    }
                }else{
                    bits[ver_v]=2;
                }
            }
        }
        for(int i=0;i<wektor[(it_wek-1)%2][ver_v].size();i++){
            if(drzewo[ver_i][wektor[(it_wek-1)%2][ver_v][i].first]){
                b=krok(start,drzewo[ver_i][wektor[(it_wek-1)%2][ver_v][i].first],wektor[(it_wek-1)%2][ver_v][i].second)||b;
            }
        }
    }
    return b;
}

int main(){
    int n, l;
    scanf("%d%d",&n,&m);
    int it=1;
    int v;
    int tmp;
    int it2=1;
    for(int i=0;i<n;i++){
        scanf("%d",&l);
        v=0;
        for(int k=0;k<=l;k++){
            v2[k]=0;
        }
        for(int j=0;j<l;j++){
            scanf("%d",&tmp);
            tmp--;
            if(drzewo[v][tmp]){
                v=drzewo[v][tmp];
            }else{
                drzewo[v][tmp]=it;
                v=it++;
            }
            index3[v].push_back(i);
            for(int k=0;k<=j;k++){
                if(drzewo2[v2[k]][tmp]){
                    v2[k]=drzewo2[v2[k]][tmp];
                }else{
                    drzewo2[v2[k]][tmp]=it2;
                    v2[k]=it2++;
                }
                if(index4[v2[k]].empty()||index4[v2[k]][index4[v2[k]].size()-1]!=i){
                    index4[v2[k]].push_back(i);
                }
            }
            if(j==l-1){
                index[v].push_back(i);
                for(int k=0;k<=j;k++){
                    if(index2[v2[k]].empty()||index2[v2[k]][index2[v2[k]].size()-1]!=i) index2[v2[k]].push_back(i);
                }
            }
        }
    }
    for(int i=0;i<m;i++){
        scanf("%d",&tmp);
        tmp--;
        wektor[0][i].push_back(make_pair(tmp,i+1));
    }
    /*for(int i=0;i<it2;i++){
        cout<<i<<": ";
        for(int j=0;j<n;j++){
            cout<<drzewo2[i][j]<<" ";
        }
        cout<<endl;
    }*/
    while(krok(0,0,0)){
        //cout<<"-----"<<endl;
        if(DONE) break;
        it_wek++;
        if(it_wek==100000) break;
        for(int i=0;i<m;i++){
            bits[i]=0;
            wektor[it_wek%2][i].clear();
        }
    }
    if(DONE) printf("%d",it_wek+1);
    else printf("-1");
/*
    for(int i=0;i<=it_wek;i++){
        cout<<"IT_WEK "<<i<<endl;
        for(int j=0;j<m;j++){
            cout<<j<<" ";
            for(int k=0;k<wektor[i][j].size();k++){
                cout<<wektor[i][j][k].first+1<<" ";
            }
            cout<<endl;
        }
    }*/
}