#include<bits/stdc++.h>

using namespace std;

#define pb push_back

const int maxi=1e6+10;

int a[maxi];
vector<int> v[maxi];
long long n;
string s;
int q;
long long b1,c1,s1,b2,c2,s2;
long long rez[maxi];

long long seq(long long b, long long c, long long s, long long val)
{
    c-=val;

    if ((b*b)/(4.00)<c) return 0;

     double det = sqrt(b*b-4.00*c);
    double x1 = ceil((-b - det)/2);
    double x2= floor((-b + det)/2);

    if (x1>x2) return 0;
    if (s>x2) return 0;

    if (s<=x1) {
            if (x2-x1>=1e9) return 1000000000; else
            return (long long) (x2-x1+1);
    }

    if (x2-s>=1e9) return 1000000000; else
            return (long long) (x2-s+1);

}


void print()
{
   freopen("sequences.out","w",stdout);
    for (int i=1;i<=q;i++)
        printf("%lld\n",rez[i]);
    fclose(stdout);
}

void solve(int query)
{
    long long l = -4e18-1e10;
    long long r=  4e18+1e10;

    for (int i=0;i<=60;i++)
    {
       long long mid = (l+r)/2;
       if (seq(b1,c1,s1,mid)+seq(b2,c2,s2,mid)>=n) r = mid; else l = mid;
    }

    rez[query] = r;
}

void read()
{
   freopen("sequences.in","r",stdin);

   cin>>q;


   for (int i=1;i<=q;i++)
   {
       scanf("%lld%lld%lld%lld%lld%lld%lld",&b1,&c1,&s1,&b2,&c2,&s2,&n);
       solve(i);
   }
    fclose(stdin);
}

int main()
{

    read();
    print();

   return 0;
}