#include <bits/stdc++.h>
using namespace std;

using ll = long long;

ll calc(ll x, ll d) {
    ll sum = 0;
    int k = 0;
    while (sum < x) {
        sum = sum * 2 + d;
        ++k;
    }
    return k;
}

// 嘘解法：RL ペアでは必ず右側を先に完成させる
ll pair_cost(ll D, ll A, ll B) {
    ll l = 0, r = D;
    ll gl = A, gr = D - B;
    ll res = 0;

    while (r > gr) {
        r = max(gr, (l + r + 1) / 2);
        ++res;
    }
    while (l < gl) {
        l = min(gl, (l + r) / 2);
        ++res;
    }

    return res;
}

int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);

    int Q;
    cin >> Q;

    while (Q--) {
        int N, M;
        cin >> N >> M;

        vector<pair<int, int>> A(M);
        for (auto& [s, g] : A) cin >> s;
        for (auto& [s, g] : A) cin >> g;

        sort(A.begin(), A.end());

        bool ok = true;
        for (int i = 1; i < M; ++i) {
            auto [s1, g1] = A[i - 1];
            auto [s2, g2] = A[i];

            if (g1 > g2 ||
                (g1 == g2 && !(s1 == s2 && s1 == g1))) {
                ok = false;
                break;
            }
        }

        if (!ok) {
            cout << -1 << '\n';
            continue;
        }

        vector<int> type(M);
        for (int i = 0; i < M; ++i) {
            auto [s, g] = A[i];
            if (s < g) type[i] = 1;
            if (s > g) type[i] = -1;
        }

        vector<bool> paired(M);
        ll ans = 0;

        for (int i = 0; i + 1 < M; ++i) {
            if (type[i] == 1 && type[i + 1] == -1) {
                paired[i] = paired[i + 1] = true;

                auto [s1, g1] = A[i];
                auto [s2, g2] = A[i + 1];

                ans += pair_cost(
                    s2 - s1,
                    g1 - s1,
                    s2 - g2
                );
            }
        }

        for (int i = 0; i < M; ++i) {
            if (paired[i]) continue;

            auto [s, g] = A[i];

            if (type[i] == 1) {
                if (i + 1 == M) ++ans;
                else ans += calc(g - s, A[i + 1].second - g);
            }

            if (type[i] == -1) {
                if (i == 0) ++ans;
                else ans += calc(s - g, g - A[i - 1].second);
            }
        }

        cout << ans << '\n';
    }
}