#include <iostream>
using namespace std;
int n, m;
long long ans;
long long arr[25];
long long goal;
void solve(int cur_index, long long cur_mask, int cur_ans) {
if ((cur_mask ^ arr[cur_index]) == goal) {
cur_ans += (1ll << (m-cur_index-1));
ans = max(ans, (long long)cur_ans);
return;
}
if (cur_index == m) {
return;
}
solve(cur_index + 1, cur_mask ^ arr[cur_index], cur_ans + (1ll << (m-cur_index-1)));
solve(cur_index + 1, cur_mask, cur_ans);
}
int main() {
cin >> n >> m;
goal = (1ll << n) - 1;
for(int i = 0; i < m; i++) {
int q; cin >> q;
for(int j = 0; j < q; j++) {
int x; cin >> x;
arr[i] += 1ll << (x-1);
}
}
solve(0, 0, 0);
cout << __builtin_popcountll(ans) << endl;
for(int i = 1; i <= m; i++) {
if (ans & (1ll << (m-i))) {
cout << i << " ";
}
}
cout << endl;
}
