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

#define REP(i, n) for(int i=0; i<(n); i++)

#define ALL(a) (a).begin(),(a).end()
int N,M;
vector<int> A, B;
signed main()
{
    cin>>N;
    A.resize(N);
    REP(i,N) cin >> A[i];
    cin>>M;
    B.resize(M);
    REP(i,M) cin >> B[i];
    sort(ALL(B), greater<int>());
    int minbox = 100;
    do {
        int bi = 0;
        int space = B[bi++]; // 大きい物順に入れる
        bool error = false;
        REP(i,A.size()) {
            if (space >= A[i]) {
                space -= A[i];
            } else {
                space = B[bi++];
                if (space < A[i]) {
                    // 失敗
                    error = true;
                    break;
                }
                i--;
            }
        }
        if (!error) minbox = min(minbox, bi);
    }while(next_permutation(ALL(A)));

    cout << ((minbox < 100) ? minbox : -1) << endl;
    return 0;
}