#include <bits/stdc++.h>
using namespace std;
template <typename A>
ostream &operator<<(ostream &cout, vector<A> const &v);
template <typename A, typename B>
ostream &operator<<(ostream &cout, pair<A, B> const &p) {
  return cout << "(" << p.first << ", " << p.second << ")";
}
template <typename A>
ostream &operator<<(ostream &cout, vector<A> const &v) {
  cout << "[";
  for (int i = 0; i < v.size(); i++) {
    if (i) cout << ", ";
    cout << v[i];
  }
  return cout << "]";
}
template <typename A, typename B>
istream &operator>>(istream &cin, pair<A, B> &p) {
  cin >> p.first;
  return cin >> p.second;
}
mt19937_64 rng(std::chrono::steady_clock::now().time_since_epoch().count());
void usaco(string filename) {
  freopen((filename + ".in").c_str(), "r", stdin);
  freopen((filename + ".out").c_str(), "w", stdout);
}
const long double pi = 3.14159265358979323846;
const long long mod = 1000000007;
struct dsu {
  int n;
  vector<int> sizes, marks;
  vector<vector<int>> graph;
  void init(int rn) {
    n = rn;
    sizes = vector<int>(n);
    fill(sizes.begin(), sizes.end(), 1);
    marks = vector<int>(n);
    for (int i = 0; i < n; i++) marks[i] = i;
    graph = vector<vector<int>>(n);
  }
  void mark(int m, int node) {
    if (marks[node] == m) return;
    marks[node] = m;
    for (int i : graph[node]) mark(m, i);
  }
  bool merge(int a, int b) {
    if (marks[a] == marks[b]) return 0;
    graph[a].push_back(b);
    graph[b].push_back(a);
    if (sizes[marks[a]] > sizes[marks[b]]) swap(a, b);
    sizes[marks[b]] += sizes[marks[a]];
    sizes[marks[a]] = 0;
    mark(marks[b], a);
    return 1;
  }
  int find(int n) { return marks[n]; }
};
long long n, m, k, q, l, r, x, y, z;
const long long template_array_size = 1e6 + 6884;
long long a[template_array_size];
long long b[template_array_size];
long long c[template_array_size];
string second, t;
long long ans = 0;
pair<long long, pair<long long, long long>> vals[200005];
long long root[100005];
bool cnt[100005];
dsu d;
void solve(int tc = 0) {
  cin >> m >> n;
  for (long long i = 0; i < m; i++) cin >> a[i];
  for (long long i = 0; i < n; i++) cin >> b[i];
  long long ans = 0, second = 0;
  for (long long i = 0; i < m; i++) {
    cin >> x;
    for (long long j = 0; j < x; j++) {
      cin >> y;
      --y;
      ans += a[i] + b[y];
      vals[second++] = make_pair(-a[i] - b[y], make_pair(i, y));
    }
  }
  sort(vals, vals + second);
  memset(cnt, 0, sizeof(cnt));
  d.init(n);
  for (long long i = 0; i < second; i++) {
    long long a = vals[i].second.first, b = vals[i].second.second,
              val = vals[i].first;
    if (!cnt[a]) {
      cnt[a] = 1;
      root[a] = b;
      ans += val;
    } else {
      if (d.merge(root[a], b)) ans += val;
    }
  }
  cout << ans << '\n';
}
int main() {
  { ios_base::sync_with_stdio(false); }
  { cin.tie(NULL); }
  cout << setprecision(12) << fixed;
  int tc = 1;
  for (int t = 0; t < tc; t++) solve(t);
}
