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

int main() {
    int t;
    cin >> t;
    while (t--) {
        int n;
        cin >> n;
        string s;
        cin >> s;


        int start = 10;
        int end = 0;
        int max_consecutive = 0;


        for (int i = 0; i < n; i++) {
            if (s[i] == '1') {
                start = min(start, i);
                end = max(end, i);
                max_consecutive = max(max_consecutive, end - start + 1);
            }
        }


        cout << max_consecutive << endl;
    }
    return 0;
}