C++ :

#include<bits/stdc++.h>
using namespace std;
long long t,a,b,x,y,n;
long long f1(long long a,long long b,long long x,long long y,long long n)
{
	int w=a-x;
	if(w>=n) {a-=n;return a*b;} 
	else{
		a=x;n-=w;b-=n;
		return a*b;
	}
}
long long f2(long long a,long long b,long long x,long long y,long long n)
{
	int w=b-y;
	if(w>=n) {b-=n;return a*b;} 
	else{
		b=y;n-=w;a-=n;
		return a*b;
	}
}
int main()
{
	cin>>t;
	while(t--)
	{
		cin>>a>>b>>x>>y>>n;
		if(a-x+b-y<=n) {cout<<x*y<<endl;continue;}
		long long xx=f1(a,b,x,y,n),yy=f2(a,b,x,y,n);
		if(xx>yy) cout<<yy<<endl;
		else cout<<xx<<endl;
	}
    return 0;
}