#include <bits/stdc++.h>
using namespace std;
typedef long long int ll;
typedef pair<ll,ll> P;
typedef vector<ll> VI;
typedef vector<VI> VVI;
#define REP(i,n) for(int i=0;i<(n);i++)
#define ALL(v) v.begin(),v.end()
template<typename T> bool chmax(T& x, const T& y){return (x<y)?(x=y,true):false;};
template<typename T> bool chmin(T& x, const T& y){return (x>y)?(x=y,true):false;};
constexpr ll MOD=998244353;
constexpr ll INF=2e18;

void solve(){
    ll n, m; cin >> n >> m;
    VI l(n), r(n);
    REP(i,n) cin >> l[i];
    REP(i,n) cin >> r[i];
    ll lsum=0, rsum=0;
    REP(i,n) lsum+=l[i];
    REP(i,n) rsum+=r[i];
    if(m<lsum||rsum<m){
        cout << -1 << endl;
        return;
    }
    ll x=0, y=2e9;
    ll rem=INF;
    while(y-x>1){
        ll z=(x+y)/2;
        ll sum=0;
        REP(i,n){
            if(z<l[i])
                sum+=l[i];
            else if(r[i]<z)
                sum+=r[i];
            else
                sum+=z;
        }
        if(sum<=m){
            x=z;
            chmin(rem,m-sum);
        }
        else
            y=z;
    }
    VI a;
    REP(i,n){
        if(x<l[i])
            a.push_back(l[i]);
        else if(r[i]<=x)
            a.push_back(r[i]);
        else{
            if(rem-->0)
                a.push_back(x+1);
            else
                a.push_back(x);
        }
    }
    ll ans=0, sum=0;
    REP(i,n){
        ans+=sum*a[n-1-i];
        sum+=a[n-1-i];
    }
    cout << ans << endl;
}

int main(){
    int t; cin >> t;
    while(t--) solve();
    return 0;
}