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#include <bits/stdc++.h>
using namespace std;
using pii = pair<int, int>;
#define FR first
#define SD second

bool cmp(pii a, pii b)
{
	if (abs(a.FR - b.FR) <= 2 && (a.SD == 1 || b.SD == 1))
	{
		if (a.SD == 1 && b.SD == 0)
			return 1;
		if (a.SD == 0 && b.SD == 1)
			return 0;
		if (a.SD == 1 && b.SD == 1)
			return a.FR > b.FR;
	}

	return a.FR > b.FR;
}

void solve()
{
	int n; cin >> n;
	vector<pii> seg;
	int cnt = 0;
	bool st = 1;
	string s; cin >> s;
	for (int i=0; i<n; i++)
	{
		if (s[i] == '0')
			cnt++;
		else
		{
			if (cnt > 0)
			{
				seg.push_back({cnt, (st && cnt > 1)});
				cnt = 0;
			}
			st = 0; 
		}
	}
	if (cnt > 0)
		seg.push_back({cnt, (cnt > 1)});

	sort(seg.begin(), seg.end(), cmp);

/*	for (auto p : seg)
		cout << "[" << p.FR << "," << p.SD << "]\n";*/

	int safe = 0, time = 0;
	for (auto p : seg)
	{
		// cout << p.FR << " -> ";
		p.FR -= (!p.SD+1)*time;
		// cout << p.FR << "\n";

		if (p.FR <= 0)
			break;

		if (p.FR == 1)
		{
			safe++;
			time++;
			continue;
		}

		if (p.SD == 0)
		{
			safe += p.FR - 1;
			time += 2;
		}
		else
		{
			safe += p.FR;
			time++;
		}
	
		// cout << safe << " " << time << "\n";
	}

	cout << n - safe << "\n";
}

int main()
{
	ios_base::sync_with_stdio(0);
	cin.tie(0); cout.tie(0);

	int t; cin >> t;
	while (t--)
		solve();
	
	return 0;
}