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#include <iostream>
#include <string>
#include <algorithm>
#include <queue>

using namespace std;


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

    for (int test_case = 0; test_case < t; ++test_case) {
        int n;
        string sick;
        cin >> n >> sick;

        priority_queue<int> healthy_lengths;
        int current_length = 0;
        int left = -1, right;

        for (char bit : sick) {
            if (bit == '1') {
                if (left < 0) {
                    left = current_length;
                } else {
                    healthy_lengths.push(current_length);
                }

                current_length = 0;
            } else {
                current_length++;
            }
        }
        right = current_length;
        left = max(0, left);

        int vaccinated_cities = 0;
        int days = 0;


        while (!healthy_lengths.empty() && healthy_lengths.top() - 2 * days > 3) {
            int length = healthy_lengths.top();
            healthy_lengths.pop();

            if (length - 2 * days == 1 || length - 2 * days == 2) {
                vaccinated_cities++;
                days++;
            } else if (length - 2 * days - 1 > 0) {
                vaccinated_cities += length - 2 * days - 1;
                days += 2;
            }
        }

        if (left - days > 0) {
            vaccinated_cities += left - days;
            days++;
        }
        if (right - days > 0) {
            vaccinated_cities += right - days;
            days++;
        }

        int length = healthy_lengths.top();
        healthy_lengths.pop();
        if (length - 2 * days == 1 || length - 2 * days == 2) {
            vaccinated_cities++;
            days++;
        }

        cout << n - vaccinated_cities << '\n';
    }

    return 0;
}