#include<bits/stdc++.h>

using namespace std;

int aa[100],bb[100];
int n,m;

map<vector<int>,int> dp;

int calc(int idx,vector<int> &weight){
    if (idx<0) {
        return 0;
    }
    if (idx<n-1){
        weight[m]=idx;
        if (dp.count(weight)) return dp[weight];
    }
    
    int min=99,r,l=99;
    for (int i=m-1;i>=0;i--){
        if (bb[i]-weight[i]==l) continue;
        if (weight[i]+aa[idx]<=bb[i]){
            vector<int> v=weight;
            v[i]+=aa[idx];
            r = (weight[i]==0) + calc(idx-1,v);
            if (r<min) min=r;
        }
        l=bb[i]-weight[i];
    }
    weight[m]=idx;
    dp[weight]=min;
    return min;
}

int main(){
	int i, j, k, l;

    cin >> n;
    for (i=0;i<n;i++)
        scanf("%d",aa+i);
    cin >> m;
    for (i=0;i<m;i++)
        scanf("%d",bb+i);
    
    sort(aa,aa+n);
    sort(bb,bb+m);
    
    vector<int> weight(m+1,0);
    i=calc(n-1,weight) ;
    cout <<(i>90?-1:i)<< endl;
    
	return 0;
}