#include <bits/stdc++.h>
using namespace std;
int main() {
ios::sync_with_stdio(false);cin.tie(nullptr);cout.tie(nullptr);
int n, m;
cin >> n >> m;
vector<unsigned long long> cardMasks(n, 0ULL);
for (int spell = 0; spell < m; ++spell) {
int q; cin >> q;
for (int t = 0; t < q; ++t) {
int a; cin >> a; --a; // 0-based kart indeksi
if (a >= 0 && a < n) cardMasks[a] |= (1ULL << spell);
}
}
auto ok_mask = [&](unsigned long long mask) -> bool {
for (int i = 0; i < n; ++i) {
if ((__builtin_parityll(cardMasks[i] & mask)) != 1) return false;
}
return true;
};
bool found = false;
vector<int> answer;
for (int k = 0; k <= m && !found; ++k) {
if (k == 0) {
if (ok_mask(0ULL)) {
cout << 0 << '\n' << '\n';
return 0;
}
continue;
}
vector<int> comb(k);
for (int i = 0; i < k; ++i) comb[i] = i;
while (true) {
unsigned long long mask = 0ULL;
for (int x : comb) mask |= (1ULL << x);
if (ok_mask(mask)) {
found = true;
answer = comb;
break;
}
int idx = k - 1;
while (idx >= 0 && comb[idx] == idx + m - k) --idx;
if (idx < 0) break; // bitti
++comb[idx];
for (int j = idx + 1; j < k; ++j) comb[j] = comb[j-1] + 1;
}
}
if (!found) {
cout << -1 << '\n';
return 0;
}
cout << (int)answer.size() << '\n';
for (size_t i = 0; i < answer.size(); ++i) {
if (i) cout << ' ';
cout << (answer[i] + 1);
}
cout << endl;
return 0;
}
