include <bits/stdc++.h>
using namespace std;
int main() {
// your code goes here
int t;
cin>>t;
while(t–){
long long n;
cin>>n;
vectora(n);
for(int i=0;i<n;i++){
cin>>a[i];
}
int chef_ans=a[0];
if(n==1){
cout<<1000000<<endl;
continue;
}
sort(a.begin(),a.end());
bool f=false,f2=false;
double left=0,right=0;
for(int i=0;i<n;i++){
if(chef_ans==a[i] && i==0){
f=true;
break;
}else if(chef_ans==a[i] && i==n-1){
f2=true;
break;
}else{
if(chef_ans==a[i]){
left=ceil((a[i-1]+chef_ans)/2.0);
right=floor((chef_ans+a[i+1])/2.0);
break;
}
}
}
if(f){
cout<<chef_ans<<endl;
}else if(f2){
if(n>1) cout<<1e6-ceil((chef_ans+a[n-2])/2)<<endl;
}else{
cout<<right-left+1<<endl;
}
}
}