#include <bits/stdc++.h>
using namespace std;

int main() {
  int N;
  cin >> N;
  vector<int> A(N);
  for (int i = 0; i < N; i++) cin >> A.at(i);
  int M;
  cin >> M;
  vector<int> B(M);
  for (int i = 0; i < M; i++) cin >> B.at(i);

  sort(A.rbegin(), A.rend());
  sort(B.rbegin(), B.rend());

  vector<int> C(M);
  for (int i = 0; i < N; i++) {
    for (int j = 0; j < M; j++) {
      if (A.at(i) <= B.at(j)) {
        B.at(j) -= A.at(i);
        C.at(j) = 1;
        goto NEXT;
      }
    }
    return cout << -1 << "\n", 0;
    NEXT:;
  }
  cout << accumulate(C.begin(), C.end(), 0) << "\n";
}