#include <iostream>
#include <cstring>
#include <algorithm>
const int N = 400010;
using namespace std;
int q[N];
int main()
{
int t;
cin>>t;
while(t--){
int n;
cin>>n;
int res = 0;
for(int i = 0;i<n;i++){
cin>>q[i];
q[i+n] = q[i];
}
for(int i =0,s=0;i<n*2;i++){
if(q[i]){
s++;
res = max(res,s);
}
else{
s=0;
}
}
cout<<res<<endl;
}
return 0;
}