#include <iostream>
#include <string>

using namespace std;

int main() {
    int t;
    cin >> t;

    while (t--) {
        int n;
        cin >> n;

        string s;
        cin >> s;

        int max_ones = 0, current_ones = 0;
        for (int i = 0; i < n; i++) {
            if (s[i] == '1') {
                current_ones++;
                max_ones = max(max_ones, current_ones);
            } else {
                current_ones = 0;
            }
        }

        cout << max_ones << endl;
    }

    return 0;
}