#include <bits/stdc++.h>
#pragma comment(linker, "/stack:512000000")
#pragma GCC optimize("Ofast")
#pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,tune=native")
#pragma GCC optimize("unroll-loops")
using namespace std;
using ll = long long;
using ull = unsigned long long;
using ld = long double;
mt19937_64 gen(time(nullptr));
struct custom_hash {
  static uint64_t splitmix64(uint64_t x) {
    x += 0x9e3779b97f4a7c15;
    x = (x ^ (x >> 30)) * 0xbf58476d1ce4e5b9;
    x = (x ^ (x >> 27)) * 0x94d049bb133111eb;
    return x ^ (x >> 31);
  }
  size_t operator()(uint64_t x) const {
    static const uint64_t FIXED_RANDOM =
        chrono::steady_clock::now().time_since_epoch().count();
    return splitmix64(x + FIXED_RANDOM);
  }
};
ll mod = 1e9 + 7;
namespace {
ll mul(ll a, ll b) {
  ll val = a * b - (ll)((ld)a * b / mod) * mod;
  if (val < 0) val += mod;
  if (val >= mod) val -= mod;
  return val;
}
ll poww(ll a, ll b) {
  ll val = 1;
  a %= mod;
  while (b > 0) {
    if (b % 2) val = mul(a, val);
    a = mul(a, a);
    b >>= 1;
  }
  return val % mod;
}
ll inv(ll a) { return poww(a, mod - 2); }
ll gcd(ll a, ll b) { return (a == 0 ? b : gcd(b % a, a)); }
ll gcdex(ll a, ll b, ll& x, ll& y) {
  if (a == 0) {
    x = 0;
    y = 1;
    return b;
  }
  ll x1, y1;
  ll d = gcdex(b % a, a, x1, y1);
  x = y1 - (b / a) * x1;
  y = x1;
  return d;
}
ll inv_eu(ll a, ll m) {
  ll x, y;
  ll g = gcdex(a, m, x, y);
  if (g != 1)
    assert(0);
  else {
    x = (x % m + m) % m;
    return x;
  }
}
}  // namespace
ll const maxn = 3e5 + 5;
int par[maxn], sz[maxn];
void dsu_make(int u) {
  par[u] = u;
  sz[u] = 1;
}
int dsu_get(int u) { return (par[u] == u ? u : par[u] = dsu_get(par[u])); }
void dsu_merge(int u, int v) {
  u = dsu_get(u), v = dsu_get(v);
  if (u == v) return;
  if (sz[u] < sz[v]) swap(u, v);
  par[v] = u;
  sz[u] += sz[v];
}
signed main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  int m, n;
  cin >> m >> n;
  vector<int> a(m), b(n);
  for (int i = 0; i < m; i++) cin >> a[i];
  for (int i = 0; i < n; i++) cin >> b[i];
  vector<pair<int, pair<int, int>>> kek;
  ll ans1 = 0;
  for (int i = 0; i < m; i++) {
    int s;
    cin >> s;
    for (int j = 0; j < s; j++) {
      int x;
      cin >> x;
      x--;
      kek.push_back({a[i] + b[x], {i, x}});
      ans1 += (a[i] + b[x]);
    }
  }
  ll ans = 0;
  sort(kek.begin(), kek.end());
  reverse(kek.begin(), kek.end());
  vector<vector<int>> g(n);
  for (int i = 0; i < m; i++) {
    dsu_make(i);
  }
  for (auto p : kek) {
    int x = p.first;
    int i = p.second.first, j = p.second.second;
    bool f = true;
    for (int ii : g[j]) {
      if (dsu_get(ii) == dsu_get(i)) {
        f = false;
        break;
      } else {
        break;
      }
    }
    if (f) {
      ans += x;
      for (int ii : g[j]) {
        dsu_merge(ii, i);
        break;
      }
      g[j].emplace_back(i);
    }
  }
  cout << ans1 - ans << endl;
  return 0;
}
