#include <bits/stdc++.h>
using namespace std;
const long long mod = (long long)1e9 + 7;
const long long inf = (long long)1e16;
const long double eps = 1e-12;
const long long N = (int)1e5 + 5;
const long long LOGN = 19;
const long double PI = 3.14159265358979323846;
inline long long mul(long long a, long long b, long long m = mod) {
  return (long long)(a * b) % m;
}
inline long long add(long long a, long long b, long long m = mod) {
  a += b;
  if (a >= m) a -= m;
  if (a < 0) a += m;
  return a;
}
inline long long power(long long a, long long b, long long m = mod) {
  if (b == 0) return 1;
  if (b == 1) return (a % m);
  long long x = power(a, b / 2, m);
  x = mul(x, x, m);
  if (b % 2) x = mul(x, a, m);
  return x;
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  if (0) {
    freopen("C:\\Users\\Dishant\\Desktop\\Collection-DEV c++\\input.txt", "r",
            stdin);
    freopen("C:\\Users\\Dishant\\Desktop\\Collection-DEV c++\\output.txt", "w",
            stdout);
  }
  int n;
  cin >> n;
  vector<int> a(n);
  for (int i = 0; i < n; i++) cin >> a[i];
  int m;
  cin >> m;
  vector<int> b(m);
  for (int i = 0; i < m; i++) cin >> b[i];
  int ans = 0;
  while (!a.empty() && !b.empty()) {
    if (a.back() == b.back()) {
      a.pop_back();
      b.pop_back();
      ans++;
    } else
      break;
  }
  { reverse(a.begin(), a.end()); };
  { reverse(b.begin(), b.end()); };
  while (!a.empty() && !b.empty()) {
    if (a.back() == b.back()) {
      a.pop_back();
      b.pop_back();
      ans++;
    } else
      break;
  }
  if (a.empty() && b.empty()) {
    cout << ans << endl;
    return 0;
  }
  if (a.empty() || b.empty()) {
    cout << -1;
    return 0;
  }
  long long A = 0, B = 0;
  int l = 0, r = 0;
  while (l < a.size() || r < b.size()) {
    if (A >= B) {
      if (r < b.size()) {
        B += b[r];
        r++;
      } else {
        cout << "-1";
        return 0;
      }
    } else {
      if (l < a.size()) {
        A += a[l];
        l++;
      } else {
        cout << "-1";
        return 0;
      }
    }
    if (A == B) {
      ans++;
      A = 0;
      B = 0;
    }
  }
  if (A == 0 && B == 0) {
    cout << ans << endl;
  } else
    cout << "-1\n";
  return 0;
}
