import gc
import heapq
import itertools
import math
import sqlite3
from collections import Counter, deque, defaultdict
from sys import stdout
import time
from math import factorial, log, gcd
import sys
from decimal import Decimal
import threading
from heapq import *
def S():
return sys.stdin.readline().split()
def I():
return [int(i) for i in sys.stdin.readline().split()]
def II():
return int(sys.stdin.readline())
def IS():
return sys.stdin.readline().replace('\n', '')
def main():
n, a = II(), I()
m, b = II(), I()
s1, s2 = map(sum, [a, b])
if s1 != s2:
print(-1)
return
if a == b:
print(n)
return
idx_a = 1
idx_b = 0
s_a = a[0]
s_b = 0
ans = 0
while True:
if s_a > s_b:
s_b += b[idx_b]
idx_b += 1
elif s_a < s_b:
s_a += a[idx_a]
idx_a += 1
else:
ans += 1
if idx_a == n:
break
idx_a += 1
s_a = a[idx_a - 1]
s_b = 0
print(ans)
if __name__ == '__main__':
main()#pragma GCC optimize("Ofast")
#pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,avx2,fma")
#pragma GCC optimize("unroll-loops")
#include <bits/stdc++.h>
#include <complex>
#include <queue>
#include <set>
#include <unordered_set>
#include <list>
#include <chrono>
#include <random>
#include <iostream>
#include <algorithm>
#include <cmath>
#include <string>
#include <vector>
#include <map>
#include <unordered_map>
#include <stack>
#include <iomanip>
#include <fstream>
using namespace std;
typedef long long ll;
typedef long double ld;
typedef pair<int,int> p32;
typedef pair<ll,ll> p64;
typedef pair<double,double> pdd;
typedef vector<ll> v64;
typedef vector<int> v32;
typedef vector<vector<int> > vv32;
typedef vector<vector<ll> > vv64;
typedef vector<vector<p64> > vvp64;
typedef vector<p64> vp64;
typedef vector<p32> vp32;
ll MOD = 998244353;
double eps = 1e-12;
#define forn(i,e) for(ll i = 0; i < e; i++)
#define forsn(i,s,e) for(ll i = s; i < e; i++)
#define rforn(i,s) for(ll i = s; i >= 0; i--)
#define rforsn(i,s,e) for(ll i = s; i >= e; i--)
#define dbg(x) cout<<#x<<" = "<<x<<ln
#define mp make_pair
#define pb push_back
#define fi first
#define se second
#define INF 2e18
#define fast_cin() ios_base::sync_with_stdio(false); cin.tie(NULL); cout.tie(NULL)
#define all(x) (x).begin(), (x).end()
#define sz(x) ((ll)(x).size())
void solve(){
ll n1;
cin>>n1;
ll a[n1];
ll sum1=0;
forn(i,n1){
cin>>a[i];
sum1+=a[i];
}
ll n2;
cin>>n2;
ll sum2=0;
ll b[n2];
forn(i,n2){
cin>>b[i];
sum2+=b[i];
}
if(sum1!=sum2){
cout<<-1<<endl;
return;
}
ll x=a[0],y=b[0];
ll i=1,j=1;
ll ans=0;
while(i<n1 && j<n2){
if(x<y){
x+=a[i];
i++;
}
else if(y<x){
y+=b[j];
j++;
}
else{
ans++;
x=a[i];
y=b[j];
i++;
j++;
}
}
ans++;
cout<<ans<<endl;
}
int main()
{
fast_cin();
ll t=1;
// cin >> t;
for(int ix=1;ix<=t;ix++) {
solve();
}
return 0;
}
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