#include <iostream>
#include <string>

using namespace std;

int maxConsecutiveOnes(string s) {
    int max_ones = 0, current_ones = 0;

    for (char c : s) {
        if (c == '1') {
            current_ones++;
            max_ones = max(max_ones, current_ones);
        } else {
            current_ones = 0;
        }
    }

    return max_ones;
}

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

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

        string s;
        cin >> s;

        int result = maxConsecutiveOnes(s);
        cout << result << endl;
    }

    return 0;
}