#include <iostream>
#include <vector>
#include <algorithm>
#include <climits>
using namespace std;
int main(){
  int N; cin>>N;
  vector<int> v1(N);
  for(int i=0;i<N;++i){
    cin>>v1[i];
  }
  int M; cin>>M;
  vector<int> v2(M);
  for(int i=0;i<M;++i){
    cin>>v2[i];
  }
  sort(v1.begin(),v1.end());
  sort(v2.begin(),v2.end(),greater<int>());
  int ans1=INT_MAX;
  do{
    vector<int> v3=v1;
    vector<int> v4=v2;
    for(int i=0;i<N;++i){
      int a=v3[i];
      for(int j=0;j<M;++j){
        int b=v4[j];
        if(a<=b){
          v3[i]-=a;
          v4[j]-=a;
          break;
        }
      }
    }
    int sum1=0;
    for(int i=0;i<N;++i){
      sum1+=v3[i];
    }
    if(sum1==0){
      int box1=0;
      for(int i=0;i<M;++i){
        if(v2[i]!=v4[i]) box1+=1;
      }
      if(ans1>box1) ans1=box1;
    }
  } while(next_permutation(v1.begin(),v1.end()));
  if(ans1==INT_MAX) ans1=-1;
  cout<<ans1<<endl;
}