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#include <iostream>
#include <vector>
#include <algorithm>

using namespace std;

int main() {
	ios_base::sync_with_stdio(false);

	int T;
	cin >> T;

	for (int t = 0; t < T; t++) {
		int N;
		cin >> N;
		string s;
		cin >> s;

		vector<int> v;
		int edge1 = 0;
		int edge2 = 0;
		bool edge = true;
		int cnt0 = 0;
		for (auto c: s) {
			if (c == '0') {
				cnt0++;
			} else {
				if (cnt0 > 0) {
					if (edge)
						edge1 = cnt0;
					else
						v.push_back(cnt0);
					cnt0 = 0;
				}
				edge = false;
			}
		}
		if (cnt0 > 0) {
			if (edge) {
				cout << "0" << endl;
				continue;
			}
			edge2 = cnt0;
		}

		sort(v.begin(), v.end());

		int days = 0;
		cnt0 = 0;
		for (auto it = v.rbegin(); it != v.rend(); it++) {
			int currentval = *it - 2*days;

			auto getedge = [&] (int &edgeval) {
				if ((edgeval - days >= currentval-1 && edgeval - days > 0) ||
						(currentval == 5 && edgeval - days == 3)) {
					cnt0 += edgeval - days;
					days++;
					edgeval = 0;
					currentval -= 2;
				}
			};

			getedge(edge2);
			getedge(edge1);

			if (currentval == 2 || currentval == 1) {
				cnt0++;
				days++;
			} else if (currentval > 0) {
				cnt0 += currentval-1;
				days += 2;
			}
		}

		if (edge1 - days > 0) {
			cnt0 += edge1 - days;
			days++;
		}
		if (edge2 - days > 0)
			cnt0 += edge2 - days;

		cout << N-cnt0 << endl;
	}

	return 0;
}