#include <iostream>
#include <string>
#include <vector>
using namespace std;

int maxConsecutiveOnes(string s) {
    int maxCount = 0, count = 0;
    for (char c : s) {
        if (c == '1') {
            count++;
        } else {
            maxCount = max(maxCount, count);
            count = 0;
        }
    }
    return max(maxCount, count); 
}

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;
}