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#define debug_printf(fmt, ...)
//#define debug_printf(fmt, ...) do { printf(fmt, __VA_ARGS__); } while (0)

#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <climits>
#include <cassert>
#include <vector>
#include <set>
#include <map>
#include <deque>
#include <algorithm>
#include <functional>
#include <random>
#include <limits>
#include <iostream>

const long long LLMAX = (std::numeric_limits<long long>()).max();
const long long LLMIN = (std::numeric_limits<long long>()).min();

const int N_max = 500;
const int M_max = 1000;
const int Sum_li_max = 1000;

int H[N_max + 1 /*1-based*/][Sum_li_max];
int H_len[N_max + 1 /*1-based*/];

const int Time_max = 65000;

std::vector<int> S[Time_max];

struct HinS {
    HinS(int h, int offset)
    {
        this->h = h;
        this->offset = offset;
    }

    int h;
    int offset;
};

std::vector<std::vector<HinS> > hinss[Time_max];

int N;
int earliest = INT_MAX;

void prepare_build_and_try(const int time);
void build_and_try(const int time, const int s);

void prepare_build_and_try(const int time)
{
    if (earliest <= time) {
        return;
    }

    for (int t=0; t < time; ++t) {
        if (S[t].size() == S[time].size()) {
            bool mismatch = false;
            for (int s=0; s < (int) S[time].size(); ++s) {
                if (S[t][s] != S[time][s]) {
                    mismatch = true;
                    break;
                }
            }
            if (!mismatch) {
                return;
            }
        }
    }

    if (S[time].size() == 1 && S[time][0] == 1) {
        earliest = time;
        return;
    }

    debug_printf("%d\n", time);

    hinss[time].clear();
    for (int i=0; i < (int) S[time].size(); ++i) {
        hinss[time].push_back(std::vector<HinS>());
    }

    for (int i=1; i <= N; ++i) {
        int* Hi = H[i];
        int Hi_len = H_len[i];
        // Find all occurrences of Hi suffixes that S starts with.
        for (int o=-Hi_len+1; o < 0; ++o) {
            bool mismatch = false;
            for (int s=0; s < (int) S[time].size() && s - o < Hi_len; ++s) {
                if (S[time][s] != Hi[s - o]) {
                    mismatch = true;
                    break;
                }
            }
            if (!mismatch) {
                hinss[time][0].push_back(HinS(i, o));
            }
        }
        // Find all occurrences of Hi inside S; also include all Hi prefixes that S ends with.
        for (int s=0; s < (int) S[time].size(); ++s) {
            bool mismatch = false;
            for (int h=0; h < Hi_len && s + h < (int) S[time].size(); ++h) {
                if (S[time][s + h] != Hi[h]) {
                    mismatch = true;
                    break;
                }
            }
            if (!mismatch) {
                hinss[time][s].push_back(HinS(i, 0));
            }
        }
    }

    build_and_try(time, 0);
}

void build_and_try(const int time, const int s)
{
    if (time + 1 == Time_max) {
        return;
    }

    if (s >= (int) S[time].size()) {
        prepare_build_and_try(time + 1);
    } else {
        for (int i=0; i < (int) hinss[time][s].size(); ++i) {
            HinS& hins = hinss[time][s][i];
            S[time + 1].push_back(hins.h);
            build_and_try(time, s + H_len[hins.h] + hins.offset);
            S[time + 1].pop_back();
        }
    }
}

int main()
{
    std::ios_base::sync_with_stdio(false);

    int M; scanf("%d %d", &N, &M);
    for (int i=0; i < N; ++i) {
        int li; scanf("%d", &li);
        H_len[i + 1] = li;
        for (int j=0; j < li; ++j) {
            int hij; scanf("%d", &hij);
            H[i + 1][j] = hij;
        }
    }
    for (int i=0; i < M; ++i) {
        int si; scanf("%d", &si);
        S[0].push_back(si);
    }

    prepare_build_and_try(0);

    printf("%d\n", (earliest != INT_MAX) ? earliest + 1 : -1);
}