#include <bits/stdc++.h>
using namespace std;
template <typename T>
ostream& operator<<(ostream& os, vector<T> v) {
  os << '[';
  string sep;
  for (const T& el : v) os << sep << el, sep = ", ";
  return os << ']';
}
void dbg_out() { cerr << endl; }
template <typename Head, typename... Tail>
void dbg_out(Head H, Tail... T) {
  cerr << ' ' << H;
  dbg_out(T...);
}
int dsu_find(vector<int>& parents, int a) {
  return (parents[a] == a) ? a : (parents[a] = dsu_find(parents, parents[a]));
}
bool dsu_union(vector<int>& parents, int a, int b) {
  int pa = dsu_find(parents, a);
  int pb = dsu_find(parents, b);
  if (pa != pb) {
    parents[pa] = pb;
    return true;
  }
  return false;
}
void run() {
  int m, n;
  cin >> m >> n;
  vector<long long> a(m + 1), b(n + 1);
  for (int i = 1; i < m + 1; i++) cin >> a[i];
  for (int j = 1; j < n + 1; j++) cin >> b[j];
  auto cost = [&](int x, int y) -> long long {
    int u = min(x, y), v = max(x, y);
    return a[u] + b[v - m];
  };
  long long tot_cost = 0;
  vector<pair<long long, pair<int, int> > > edgelist;
  for (int i = 1; i < m + 1; i++) {
    int s;
    cin >> s;
    for (int x = 0; x < s; x++) {
      int j;
      cin >> j;
      edgelist.push_back(make_pair(a[i] + b[j], make_pair(i, m + j)));
      tot_cost += (a[i] + b[j]);
    }
  }
  sort(edgelist.begin(), edgelist.end(),
       greater<pair<long long, pair<int, int> > >());
  vector<int> parents(m + n + 1);
  for (int i = 1; i < m + n + 1; i++) parents[i] = i;
  long long mst_cost = 0;
  for (pair<long long, pair<int, int> > e : edgelist) {
    ;
    if (dsu_find(parents, e.second.first) !=
        dsu_find(parents, e.second.second)) {
      mst_cost += e.first;
      dsu_union(parents, e.second.first, e.second.second);
      ;
    }
  }
  cout << tot_cost - mst_cost << '\n';
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  run();
}
