#include <stdio.h>

long long int L[200010],R[200010];
int main()
{
    int Case;
    scanf("%d",&Case);
    while(Case--)
    {
        int a;
        long long int b;
        scanf("%d%lld",&a,&b);
        for(int i=1;i<=a;i++) scanf("%lld",&L[i]);
        for(int i=1;i<=a;i++) scanf("%lld",&R[i]);
        long long int min = 0, max = 1e9;
        long long int ans = -1;
        while(min<=max)
        {
            long long int h = (min+max)/2;
            long long int s = 0, t = 0;
            for(int i=1;i<=a;i++)
            {
                if(R[i]<=h) s += R[i];
                else if(L[i]>h) s += L[i];
                else s += h, t++;
            }
            if(s>b) max = h-1;
            else if(s+t<b) min = h+1;
            else
            {
                t = b-s;
                long long int val = 0;
                for(int i=1;i<=a;i++)
                {
                    if(R[i]<=h) val += R[i]*R[i];
                    else if(L[i]>h) val += L[i]*L[i];
                    else if(t>0) val += (h+1)*(h+1), t--;
                    else val += h*h;
                }
                ans = ans>(b*b-val)/2?ans:(b*b-val)/2;
                min = h+1;
            }
        }
        printf("%lld\n",ans);
    }
}