#include <bits/stdc++.h>
using namespace std;
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace __gnu_pbds;
#define ordered_set tree<ll, null_type,less<ll>, rb_tree_tag,tree_order_statistics_node_update>
#define ll long long int
#define N (ll)1e6
int main(){
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    ll t=1,i=1,j,p,mx,tot,n,a,m,x,y,k,rt,c,b=1;
    cin>>t;
    while(t--){
        cin>>n;
        string s;
        cin>>s;
        ll cnt=0,mx=0;
        for(a=0;a<s.size();a++){
            if(s[a]=='0')
                cnt++;
            else{
                mx=max(mx,cnt);
                cnt=0;
            }
        }
        mx=max(mx,cnt);
        cout<<mx<<endl;
    }
}