#include <iostream>
#include <algorithm>
using namespace std;

int max1s(string &s) {
    int m = 0, c = 0;
    for (char x : s) {
        if (x == '1') {
            c++;
            m = max(m, c);
        } else {
            c = 0;
        }
    }
    return m;
}

int main() {
    int t;
    cin >> t;
    while (t--) {
        int n;
        cin >> n;
        string s;
        cin >> s;
        cout << max1s(s) << endl;
    }
    return 0;
}