#include <iostream>
#include <vector>
#include <algorithm>
#include <queue>
using namespace std;

using ll = long long;
using P = pair<ll, ll>;

int main() {
    int T;
    cin >> T;
    while (T--) {
        ll N, M;
        cin >> N >> M;
        vector<ll> L(N), R(N);
        for (int i = 0; i < N; i++) cin >> L[i];
        for (int i = 0; i < N; i++) cin >> R[i];

        ll sum_L = 0, sum_R = 0;
        for (int i = 0; i < N; i++) sum_L += L[i];
        for (int i = 0; i < N; i++) sum_R += R[i];
        
        if (M < sum_L || sum_R < M) {
            cout << -1 << endl;
            continue;
        }

        ll ok = 1e9, ng = 0;
        while (ok - ng > 1) {
            ll mid = (ok + ng) / 2;
            ll sum = 0;
            for (int i = 0; i < N; i++) {
                if (mid > R[i]) sum += R[i];
                else if (mid <= L[i]) sum += L[i];
                else sum += mid;
            }

            if (sum >= M) ok = mid;
            else ng = mid;
        }

        ll sum = 0;
        for (int i = 0; i < N; i++) {
            if (ok > R[i]) sum += R[i];
            else if (ok <= L[i]) sum += L[i];
            else sum += ok;
        }

        int cnt = 0;
        vector<ll> A;
        for (int i = 0; i < N; i++) {
            if (ok > R[i]) A.push_back(R[i]);
            else if (ok <= L[i]) A.push_back(L[i]);
            else {
                if (cnt < sum - M) A.push_back(ok - 1);
                else A.push_back(ok);
                cnt++;
            }
        }

        ll ans = M * (M - 1) / 2;
        for (auto a: A) ans -= a * (a - 1) / 2;
        cout << ans << endl;
    }
}