#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());

  int acc = accumulate(A.begin(), A.end(), 0);
  int mi = -1;
  for (int i = 0; i < M; i++) {
    acc -= B.at(i);
    if (acc <= 0) {
      mi = i;
      break;
    }
  }
  if (mi == -1) return cout << -1 << "\n", 0;

  vector<int> C(M);
  for (int i = 0; i < N; i++) {
    for (int j = mi; j >= 0; j--) {
      if (B.at(j) >= A.at(i)) {
        B.at(j) -= A.at(i);
        C.at(j) = 1;
        goto NEXT;
      }
    }
    for (int j = 0; j < M; j++) {
      if (B.at(j) >= A.at(i)) {
        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";
}