#include<bits/stdc++.h>
#define int long long
using namespace std;
#define rep(i,a,b) for(int i=(a);i<=(b);++i)
#define per(i,a,b) for(int i=(a);i>=(b);--i)
#define eb emplace_back
#define fi first
#define se second
#define pc __builtin_popcount
typedef pair<int,int> pii;
typedef vector<int> vi;

long long read() {
	long long res=0, w=1; char c=getchar();
	while(!isdigit(c)) {if(c=='-') w=-1; c=getchar();}
	while(isdigit(c)) {res=res*10+c-'0'; c=getchar();}
	return res*w;
}

int cp,cm,h0,a1,d1,n,T,ans;

signed main() {
	T=read();
	while(T--) {
		cp=read(), cm=read(), h0=read()-1, a1=read(), d1=read(), n=read();
		ans=max(cp*max(1ll,n),cm*(n-1));
		for(int l=1,r;l<=h0;l=r+1) {
			r=h0/(h0/l);
			int x=h0/l+1, d0=max(0ll,a1-r/cp), m=n-d0;
			//cout<<x<<" "<<l<<" "<<r<<" "<<d0<<" "<<m<<endl;
			if(m<0) continue;
			//physic
			int att=cp*max(1ll,m-d1);
			ans=max(ans,att*x);
			//cout<<"AT "<<att*x<<endl;
			//magic
			int t=m/2, k=m-t;
			if(k>x) k=x, t=m-k;
			ans=max(ans,cm*k*t+m-k);
			//cout<<"MG "<<cm*k*t+m-k<<endl;
			if(k>0) t++, k--;
			ans=max(ans,cm*k*t+m-k);
			//cout<<"MG "<<cm*k*t+m-k<<endl;
		}
		printf("%lld\n",ans);
	}
	return 0;
}