#include <bits/stdc++.h>
#define eb emplace_back
#define mp make_pair
#define fi first
#define se second
#define F(i, x, y) for (int i = (x); i <= (y); i++)
#define R(i, x, y) for (int i = (x); i >= (y); i--)
#define FIO(FILE) freopen(FILE".in", "r", stdin), freopen(FILE".out", "w", stdout)
#define int long long

using namespace std;
typedef long long ll;
typedef pair<int, int> pi;
bool Mbe;

const int N = 1e5 + 5;
const int inf = 0x3f3f3f3f3f3f3f3f;

int n;
int a[N], b[N];
int f[N][2][2];

void solve() {
	cin >> n;
	F (i, 1, n) {
		cin >> a[i];
	}
	F (i, 1, n) {
		cin >> b[i];
	}
	F (i, 1, n) {
		if (!a[i] && b[i]) {
			cout << -1 << '\n';
			return;
		}
	}
	memset(f, -0x3f, sizeof(f));
	f[0][0][0] = 0;
	F (i, 1, n) {
		if (!b[i]) {
			F (x, 0, 1) {
				F (y, 0, 1) {
					if (f[i - 1][x][y] == -inf) {
						continue;
					}
					F (u, 0, 1) {
						int _y = max({ 0ll, y + u, u });
						if (_y > 1) {
							continue;
						}
						f[i][x][_y] = max(f[i][x][_y], f[i - 1][x][y] + a[i] * u);
					}
				}
			}
		} else {
			F (x, 0, 1) {
				F (y, 0, 1) {
					if (f[i - 1][x][y] == -inf) {
						continue;
					}
					F (v, 0, 1) {
						F (w, -1, 1) {
							int _x = max({ 0ll, x + w, w });
							int _y = max({ 0ll, y - w - v, - w - v });
							if (_x > 1 || _y > 1) {
								continue;
							}
							f[i][_x][_y] = max(f[i][_x][_y], f[i - 1][x][y] + (1 - a[i]) * v + (b[i] - a[i]) * w);
						}
					}
				}
			}
		}
	}
	cout << max({ f[n][0][0], f[n][0][1], f[n][1][0], f[n][1][1] }) << '\n';
}

bool Med;
signed main() {
	// FIO("");
	ios::sync_with_stdio(0), cin.tie(0), cout.tie(0);
	cerr << (&Mbe - &Med) / 1048576.0 << " MB\n";
	int T = 1;
	cin >> T;
	while (T--) solve();
	cerr << (int)(1e3 * clock() / CLOCKS_PER_SEC) << " ms\n";
	return 0;
}