#include <iostream>
#include <new>
using namespace std;
int main() {
int t;
int *a, *d;
int i,j,k,m;
int n;
cin>>t;
while(t--){
cin>>n;
a=new int[n];
d=new int[n];
for(i=0;i<n;i++){
scanf("%d",&a[i]);
}
for(i=0;i<n;i++){
scanf("%d",&d[i]);
}
for(i=0;i<n;i++){
j=(n+(i+1))%n;
k=(n+(i-1))%n;
if((a[j]+a[k])<d[i]){
printf("%d \n",d[i]);
m=1;
break;
}
else{
m=0;
}
}
if(m==0)
printf("-1");
}
return 0;
}
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