import java.util.ArrayList;
import java.util.Collections;
import java.util.LinkedList;
import java.util.Scanner;

public class Main2 {
    static int n, m;
    static ArrayList<Integer> a, b;
    
    public static void main(String[] args) {
        try (Scanner scan = new Scanner(System.in)) {
            n = Integer.parseInt(scan.next());
            a = new ArrayList<>();
            for(int i=0; i<n; i++) {
                a.add(Integer.parseInt(scan.next()));
            }
              
            m = Integer.parseInt(scan.next());
            b = new ArrayList<>();
            for(int i=0; i<m; i++) {
                b.add(Integer.parseInt(scan.next()));
            }
            
            a.sort(Collections.reverseOrder());
            b.sort(Collections.reverseOrder());
                        
            LinkedList< ArrayList<Integer> > checkList = new LinkedList<>();
            LinkedList< ArrayList<Integer> > nextCheckList = new LinkedList<>();
            checkList.add(a);

            for(int i=0; i<b.size(); i++) {
                
                while(!checkList.isEmpty()) {
                    final ArrayList<Integer> nowList = checkList.poll();
                    
                    boolean flag = false;
                    for(Integer v : nowList) {
                        if(b.get(i) < v) {
                            flag = true;
                            break;
                        }
                    }
                    if(flag) continue;
                    
                    nodeList.clear();
                    solve(0, b.get(i), new ArrayList<Integer>(), nowList);
                    
                    for(int k=0; k<nodeList.size(); k++) {
                        ArrayList<Integer> pList = nodeList.get(k).list;
                        ArrayList<Integer> tmpList = (ArrayList<Integer>)nowList.clone();
                        
                        for(int j=0; j<pList.size(); j++) {
                            tmpList.remove(pList.get(j));
                        }
                        if(tmpList.size() == 0) {
                            System.out.println(i+1);
                            System.exit(0);
                        }
                        nextCheckList.add(tmpList);
                    }
                }
                checkList = (LinkedList< ArrayList<Integer> >)nextCheckList.clone();
                nextCheckList.clear();
            }            
            System.out.println(-1);
        }
    }
    
    static ArrayList<Node> nodeList = new ArrayList<>();
    
    static void solve(int i, int box, ArrayList<Integer> list, ArrayList<Integer> a) {
        ArrayList<Integer> tmpList = (ArrayList<Integer>)list.clone();
        
        if(i == a.size()) {
            Node node = new Node(box, (ArrayList<Integer>)list.clone());
            
            for(Node now : nodeList) {
                if(node.equals(now)) {
                    return;
                }
            }
            nodeList.add(node);
            return;
        }
        
        solve(i+1, box, tmpList, a);
        
        if((box - a.get(i)) >= 0) {
            tmpList.add(a.get(i));
            solve(i+1, box-a.get(i), tmpList, a);
        }
    }
    
    static class Node implements Comparable<Node> {
        int rem;
        ArrayList<Integer> list;
        
        Node(int rem, ArrayList<Integer> list) {
            this.rem = rem;
            this.list = list;
        }
        @Override
        public int compareTo(Node o) {
            if(rem == o.rem) {
                if(list.size() == o.list.size()) {
                    for(int i=0; i<list.size(); i++) {
                        if(list.get(i) == o.list.get(i)) continue;
                        return o.list.get(i) - list.get(i);
                    }
                    return 0;
                } else {
                    return list.size() - o.list.size();
                }
            } else {
                return rem - o.rem;
            }
        }
        @Override
        public String toString() {
            return rem + " " + list.toString();
        }
        @Override
        public boolean equals(Object obj) {
            Node t = (Node)obj;
            boolean flag = true;
            
            if(list.size() != t.list.size()) {
                flag = false;
            } else {
                for(int i=0; i<list.size(); i++) {
                    if(list.get(i) != t.list.get(i)) {
                        flag = false;
                        break;
                    }
                }
            }
            return flag;
        }
    }
}