#include <iostream>
//#include <fstream>
#include <vector>

using namespace std;

int n,k;
int x[5001];
char lin[250001];
int val[5001];
vector<int> much[5001];
int mx;

void format(int pos)
{
    pos = lin[0] - '0';
    for(int i=2;lin[i] != '\0';i+=2)
        much[pos].push_back(lin[i]-'0');
}

void citire()
{
    //ifstream f("date.in");
    cin>>n>>k;
    for(int i=1;i<=k;++i)
        cin>>x[i];
    cin.get();
    for(int i=1;i<=n;++i)
    {
        cin.get(lin, 250001);
        format(i);
        cin.get();
    }
    for(int i=0;i<5000;++i)
        val[i] = -1;
}

int parc(int i)
{
    if(val[i]>=0)
        return val[i];
    else
    {
        val[i] = 0;
        for(int j=0;j<much[i].size();++j)
            val[i] += (parc(much[i][j]) + 1);
        return val[i];
    }
}

void rez()
{
    for(int i=1;i<=k;++i){
        int a = parc(i);
        mx = ((val[i]>val[mx])||((val[i]==val[mx])&&(i<mx)))?i:mx;
    }
}

int main()
{
    citire();
    rez();
    cout<<mx;
    return 0;
}