#include<bits/stdc++.h>
using namespace std;
#define ll long long int 
int main()
{
  
        ll tc;
    cin>>tc;
    while(tc--)
    {
        ll n;
        cin>>n;
        string s;
        cin>>s;
        ll c=0,mx=0;
        for(int i=0;i<s.size();i++)
        {
            if(s[i]=='0')
            {
               c++;
                mx=max(mx,c);
            }
            else
                c=0;
        }
        cout<<mx<<endl;
    }
    


}