#include <bits/stdc++.h>
#define ll long long
#define INF 1000000005
#define MOD 1000000007
#define EPS 1e-10
#define rep(i,n) for(int i=0;i<(int)n;++i)
#define each(a, b) for(auto (a): (b))
#define all(v) (v).begin(),(v).end()
#define fi first
#define se second
#define pb push_back
#define show(x) cout<<#x<<" = "<<(x)<<endl
#define spair(p) cout<<#p<<": "<<p.fi<<" "<<p.se<<endl
#define svec(v) cout<<#v<<":";rep(kbrni,v.size())cout<<" "<<v[kbrni];cout<<endl
#define sset(s) cout<<#s<<":";each(kbrni,s)cout<<" "<<kbrni;cout<<endl
#define smap(m) cout<<#m<<":";each(kbrni,m)cout<<" {"<<kbrni.first<<":"<<kbrni.second<<"}";cout<<endl
using namespace std;

typedef pair<int,int>P;

const int MAX_N = 30;

int main()
{
    cin.tie(0);
    ios::sync_with_stdio(false);
    int n;
    cin >> n;
    vector<int> a(n);
    rep(i,n){
        cin >> a[i];
    }
    int m;
    cin >> m;
    vector<int> b(m);
    rep(i,m){
        cin >> b[i];
    }
    int sma = accumulate(all(a),0);
    int smb = accumulate(all(b),0);
    if(sma > smb){
        cout << "-1\n";
        return 0;
    }
    int ans = INF;
    do {
        int nw = 0,nv = 0;
        int i = 0;
        while(1){
            if(i == n){
                ans = min(ans,nw+1);
                break;
            }
            if(nw == m){
                break;
            }
            if(a[i] + nv <= b[nw]){
                nv += a[i];
                i++;
            }else{
                nw++;
                nv = 0;
            }
        }
    } while (next_permutation(a.begin(), a.end()));
    if(ans == INF){
        cout << "-1\n";
    }else{
        cout << ans << endl;
    }
    return 0;
}