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

using ll = long long;
const ll INF = 1LL << 60;


// 間隔 d の状態から、片側を合計 x だけ逆向きに動かすための最小操作回数
ll calc(ll x, ll d) {
    ll sum = 0;
    int k = 0;
    while (sum < x) {
        sum = sum * 2 + d;
        ++k;
    }
    return k;
}


// RL ペアのメモ化再帰
map<tuple<ll, ll, ll>, ll> memo;

ll solve_pair(ll A, ll B, ll D) {
    if (A == 0) return calc(B, D);
    if (B == 0) return calc(A, D);

    auto key = make_tuple(A, B, D);
    if (memo.count(key)) return memo[key];

    ll res = INF;

    // 次に左側を動かす
    if (A <= D) {
        res = min(res, 1 + calc(B, D + A));
    } else {
        res = min(res, 1 + solve_pair(A - D, B, 2 * D));
    }

    // 次に右側を動かす
    if (B <= D) {
        res = min(res, 1 + calc(A, D + B));
    } else {
        res = min(res, 1 + solve_pair(A, B - D, 2 * D));
    }

    return memo[key] = 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;
        }

        // 1: R, -1: L, 0: S
        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;

        // RL ペア
        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];

                ll X = g1 - s1;
                ll Y = s2 - g2;
                ll D = g2 - g1;

                ans += solve_pair(X, Y, D);
            }
        }

        // RL ペアに含まれないもの
        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';
    }
}