#include <iostream>
using namespace std;
const int N=10010;
int t,k,q[610],idx=0,a[250];
void qsort(int q[],int l,int r){
if(l>=r) return ;
int x=q[(l+r)>>1],j=r+1,i=l-1;
while(i<j){
do i++;while(q[i]<x);
do j--;while(q[j]>x);
if(i<j) swap(q[i],q[j]);
}
qsort(q,l,j);
qsort(q,j+1,r);
}
int main(){
scanf("%d",&t);k=0;
while(t--){
int n;
scanf("%d",&n);
for(int i=0;i<n;i++) scanf("%d",&q[i]);
int b;
scanf("%d",&b);
qsort(q,0,n-1);
int desk[3];
for(int j=0;j<3;j++) desk[j]=q[j]+b;
for(int j=3,i=0;j<n;j++,i++){
if(desk[i]<q[j]) desk[i]=q[j]+b;
else desk[i]+=b;
if(j==n-1){
a[k++]=desk[i];
break;
}
if(i==2) i=-1;
}
}
for(int i=0;i<k;i++){
printf("%d\n",a[i]);
}
return 0;
}