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

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

    while (T--) {
        int N;
        string S;
        cin >> N >> S; 

        int besiek = 0, runningek = 0;
        for (char i : S) {
            if (i == '1') {
                runningek++; 
                besiek = max(besiek, runningek); 
            } else {
                runningek = 0;  
            }
        }
     cout << besiek << endl;  
    }
}