#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
#define endl '\n';


bool comp(pair<int,int>a, pair<int,int>b){
    return a.first > b.first;
}



void tc(){
    int t;
    cin >> t;
    while (t--){
        ll n;
        cin >> n;
        string s;
        cin >> s;

        ll cnt = 1;

        ll ans = 0;

        for(int i = 0; i < n; i++){
            if(s[i] == '0'){
                ++i;
                while(s[i] != '1' && i < n){
                    ++cnt;
                    ++i;
                }
                ans = max(ans,cnt);
                cnt = 1;
            }
        }

        cout << ans << endl;




    }

  
}


int main()
{

    ios::sync_with_stdio(0);
    cin.tie(0);

    tc();


    return 0;
}