#include<bits/stdc++.h>
using namespace std;
using ll = long long;
using pll = pair<ll, ll>;
#define drep(i, cc, n) for (ll i = (cc); i <= (n); ++i)
#define rep(i, n) drep(i, 0, n - 1)
#define all(a) (a).begin(), (a).end()
#define pb push_back
#define fi first
#define se second
mt19937_64 rng(chrono::system_clock::now().time_since_epoch().count());
const ll MOD1000000007 = 1000000007;
const ll MOD998244353 = 998244353;
const ll MOD[3] = {999727999, 1070777777, 1000000007};
const ll LINF = 1LL << 60LL;
const int IINF = (1 << 30) - 1;


void solve(){
    ll N, M; cin >> N >> M;
    vector<ll> L(N), R(N);
    for(ll i=0; i<N; i++) cin >> L[i];
    for(ll i=0; i<N; i++) cin >> R[i];

    ll lsum = 0; for(ll i=0; i<N; i++) lsum += L[i];
    ll rsum = 0; for(ll i=0; i<N; i++) rsum += R[i];
    if(lsum > M || rsum < M){
        cout << -1 << '\n';
        return;
    }

    vector<pll> A(N);
    for(ll i=0; i<N; i++) A[i] = {L[i], i};
    sort(all(A), greater<pll>());

    vector<ll> cnt(N, -1);
    ll S = M;
    ll C = N;
    for(ll i=0; i<N; i++){
        if((S+C-1)/C <= A[i].fi){
            S -= A[i].fi;
            C--;
            cnt[A[i].se] = A[i].fi;
        }
    }
    
    vector<pll> B(N);
    for(ll i=0; i<N; i++) B[i] = {R[i], i};
    sort(all(B));
    for(ll i=0; i<N; i++){
        if(cnt[B[i].se]!=-1) continue;
        if(B[i].fi <= S/C){
            S -= B[i].fi;
            C--;
            cnt[B[i].se] = B[i].fi;
        }
    }
    
    ll now = 0;
    for(ll i=0; i<N; i++) if(cnt[i]==-1){
        cnt[i] = S/C;
        if(now<S%C){
            cnt[i]++;
            now++;
        }
    }

    ll ans = 0;
    ll sum = 0;
    for(ll i=N-1; i>=0; i--){
        ans += sum * cnt[i];
        sum += cnt[i];
    }

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

int main(){
    cin.tie(nullptr);
    ios::sync_with_stdio(false);
    
    int T=1;
    cin >> T;
    while(T--) solve();
}