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

void testcase() {
	int n;
	cin >> n;
	string s;
	cin >> s;
	priority_queue <int> Q1, Q2;
	int ones = 0;
	for (int i = 0; i < n; i++) {
		if (s[i] == '1') {
			ones++;
			continue;
		}
		int j = i;
		while (j+1 < n && s[j+1] == '0') j++;
		if (i == 0 || j == n-1) {
			Q1.push(j-i+1);
		}
		else {
			Q2.push(j-i+1);
		}
		i = j;
	}
	int t = 0, saved = 0;
	bool anything_saved;
	for (anything_saved = true ; anything_saved; t++) {
		anything_saved = false;
		if (!Q1.empty() && !Q2.empty()) {
			int r1 = Q1.top(), r2 = Q2.top();
			if (r1-t > 0 && r2-2*t > 0) {
				int cl1 = r1-t, cl2 = r2-2*t;
				int lost1 = min(3, cl2);
				int lost2 = min(1, cl2-1) + min(2, cl1);
				if (lost1 <= lost2) {
					anything_saved = true;
					saved += cl1;
					Q1.pop();
					continue;
				}
				else {
					anything_saved = true;
					saved++;
					Q2.pop();
					Q1.push(cl2-1);
					continue;
				}
			}
		}
		if (!Q2.empty()) {
			int r = Q2.top();
			if (r-2*t > 0) {
				anything_saved = true;
				saved++;
				Q2.pop();
				Q1.push(r-2*t-1);
				continue;
			}
		}
		if (!Q1.empty()) {
			int r = Q1.top();
			if (r - t > 0) {
				anything_saved = true;
				saved += r-t;
				Q1.pop();
				continue;
			}
		}
	}
	cout << n-saved <<endl;
}

int main() 
{
	ios_base::sync_with_stdio(false);
	int T;
	cin >> T;
	for (int t = 0; t < T; t++) {
		testcase();
	}
	return 0;
}