#include <bits/stdc++.h>
using namespace std;
long long gcd(long long a, long long b) { return b ? gcd(b, a % b) : a; }
long long lcm(long long a, long long b) { return a / gcd(a, b) * b; }
long long powmod(long long a, long long b, long long MOD) {
  if (a == 0ll) {
    return 0ll;
  }
  a %= MOD;
  long long ans = 1;
  while (b) {
    if (b & 1) {
      ans = ans * a % MOD;
    }
    a = a * a % MOD;
    b >>= 1;
  }
  return ans;
}
long long poww(long long a, long long b) {
  if (a == 0ll) {
    return 0ll;
  }
  long long ans = 1;
  while (b) {
    if (b & 1) {
      ans = ans * a;
    }
    a = a * a;
    b >>= 1;
  }
  return ans;
}
void Pv(const vector<int> &V) {
  int Len = int(V.size());
  for (int i = 0; i < Len; ++i) {
    printf("%d", V[i]);
    if (i != Len - 1) {
      printf(" ");
    } else {
      printf("\n");
    }
  }
}
void Pvl(const vector<long long> &V) {
  int Len = int(V.size());
  for (int i = 0; i < Len; ++i) {
    printf("%lld", V[i]);
    if (i != Len - 1) {
      printf(" ");
    } else {
      printf("\n");
    }
  }
}
inline long long readll() {
  long long tmp = 0, fh = 1;
  char c = getchar();
  while (c < '0' || c > '9') {
    if (c == '-') fh = -1;
    c = getchar();
  }
  while (c >= '0' && c <= '9') tmp = tmp * 10 + c - 48, c = getchar();
  return tmp * fh;
}
inline int readint() {
  int tmp = 0, fh = 1;
  char c = getchar();
  while (c < '0' || c > '9') {
    if (c == '-') fh = -1;
    c = getchar();
  }
  while (c >= '0' && c <= '9') tmp = tmp * 10 + c - 48, c = getchar();
  return tmp * fh;
}
void pvarr_int(int *arr, int n, int strat = 1) {
  if (strat == 0) {
    n--;
  }
  for (int i = strat; i <= n; i++) {
    printf("%d%c", arr[i], i == n ? '\n' : ' ');
  }
}
void pvarr_LL(long long *arr, int n, int strat = 1) {
  if (strat == 0) {
    n--;
  }
  for (int i = strat; i <= n; i++) {
    printf("%lld%c", arr[i], i == n ? '\n' : ' ');
  }
}
const int maxn = 1000010;
const int inf = 0x3f3f3f3f;
int n, m;
long long a[maxn], b[maxn];
struct node {
  int f, t;
  long long val;
  node() {}
  node(int ff, int tt, long long vv) {
    f = ff;
    t = tt;
    val = vv;
  }
  bool operator<(const node &bb) const { return val > bb.val; }
};
std::vector<node> v;
int far[maxn];
void dsu_init(int n) {
  for (int i = 0; i <= n; i++) {
    far[i] = i;
  }
}
int findpar(int x) {
  if (x == far[x]) {
    return x;
  } else {
    return far[x] = findpar(far[x]);
  }
}
void mg(int x, int y) {
  x = findpar(x);
  y = findpar(y);
  if (x == y) return;
  far[x] = y;
}
long long maxst() {
  dsu_init(n + m);
  sort((v).begin(), (v).end());
  long long res = 0ll;
  for (auto e : v) {
    int x = e.f;
    int y = e.t;
    x = findpar(x);
    y = findpar(y);
    if (x != y) {
      res += e.val;
      far[x] = y;
    }
  }
  return res;
}
int main() {
  m = readint();
  n = readint();
  for (int i = 1; i <= m; i++) {
    a[i] = readll();
  }
  for (int i = 1; i <= n; i++) {
    b[i] = readll();
  }
  long long ans = 0ll;
  for (int i = 1; i <= m; i++) {
    int k = readint();
    while (k--) {
      int x = readint();
      ans += a[i] + b[x];
      v.push_back(node(i, m + x, a[i] + b[x]));
      v.push_back(node(m + x, i, a[i] + b[x]));
    }
  }
  printf("%lld\n", ans - maxst());
  return 0;
}
