#include <bits/stdc++.h>
using namespace std;

int main()
{
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    int t;
    cin >> t;
    while (t--)
    {
        int n;
        vector <int> v;
        int cnt1 = 0;
        cin >> n;
        string s;
        cin >> s;
        for (int i = 0; i < n; i++)
        {
            if (s[i] == '0') s[i] = '1';
            else s[i] = '0';
        }
        for (int i = 0; i < n; i++)
        {
            if (s[i] == '1'){
                cnt1++;
                if (i == n-1)
                {
                    v.push_back(cnt1);
                }
            }
            else{
                v.push_back(cnt1);
                cnt1 = 0;
            }
        }
        cout << *max_element(v.begin(), v.end()) << "\n";

    }
    
}