import java.math.*;
import java.util.*;
 
public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n= sc.nextInt();
        int[] omo = new int[n];
        for(int i=0;i<n;i++){
        	omo[i]=sc.nextInt();
        }
        Arrays.sort(omo);
        int m = sc.nextInt();
        int[] hako =new int[m];
        boolean[] use = new boolean[m];
        for(int i=0;i<m;i++){
        	hako[i]=sc.nextInt();
        }
        Arrays.sort(hako);
        for(int i=n-1;i>=0;i--){
        	for(int j=m-1;j>=0;j--){
        		if(omo[i]<=hako[j]){
        			hako[j]-=omo[i];
        			use[j]=true;
        			break;
        		}else{
        			if(j==-1){
        				System.out.println(-1);
        			}
        			continue;
        		}
        	}
        }
        int ans=0;
        for(int i=0;i<m;i++){
        	if(use[i])ans++;
        }
        System.out.println(ans);
        
    }
}