#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_count = 0, current_count = 0;
        for (char c : S) {
            if (c == '1') {
                current_count++;
                max_count = max(max_count, current_count);
            } else {
                current_count = 0;
            }
        }

        cout << max_count << endl;
    }

    return 0;
}