#include<iostream>
#include<vector>
#include<algorithm>
#include<cassert>
using namespace std;
int N,M;
int L[2<<17],R[2<<17];
int main()
{
	ios::sync_with_stdio(false);
	cin.tie(nullptr);
	int T;cin>>T;
	for(;T--;)
	{
		cin>>N>>M;
		long sL=0,sR=0;
		for(int i=0;i<N;i++)
		{
			cin>>L[i];
			sL+=L[i];
		}
		for(int i=0;i<N;i++)
		{
			cin>>R[i];
			sR+=R[i];
		}
		if(M<sL||sR<M)
		{
			cout<<"-1\n";
			continue;
		}
		int mnl=-1,mnr=1e9;
		while(mnr-mnl>1)
		{
			int mid=(mnl+mnr)/2;
			long s=0;
			for(int i=0;i<N;i++)
			{
				if(mid<L[i])s+=L[i];
				else if(R[i]<mid)s+=R[i];
				else s+=mid;
			}
			if(s>=M)mnr=mid;
			else mnl=mid;
		}
		vector<pair<int,int> >cnt(N);
		long s=0;
		for(int i=0;i<N;i++)
		{
			int now=mnr<L[i]?L[i]:mnr>R[i]?R[i]:mnr;
			cnt[i]=make_pair(now,i);
			s+=now;
		}
		assert(0<=s-M&&s-M<N);
		sort(cnt.begin(),cnt.end());
		long ans=(long)M*(M-1)/2;
		for(int i=cnt.size();i--;)
		{
			int v=cnt[i].first;
			int id=cnt[i].second;
			if(s>M)
			{
				if(L[id]<v)v--,s--;
			}
			ans-=(long)v*(v-1)/2;
		}
		assert(s==M);
		cout<<ans<<"\n";
	}
}