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

using namespace std;

void solve(int tc) {
	int c;
	string i;
	vector<int> b;
	int s = 0;
	int e = 0;

	cin >> c >> i;
	for (int p = 0; p < c; ++p) {
		while (p < c && i[p] == '1') {
			++p;
		}
		int z = 0;
		while (p < c && i[p] == '0') {
			++p;
			++z;
		}

		if(z > 0){
			if(z == p){
				s = z;
			} else if (p == c){
				e = z;
			} else {
				b.push_back(z);
			}
		}
	}

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

	int t = 0;
	int r = 0;
	while(true){
		int st = s - t;
		int et = e - t;
		int bl = b.size() > 0 ? b.back() - 2 * t : 0;
		int sd = st;
		int ed = et;
		int bd = (bl + 1 ) / 2;

		if(sd <= 0 && ed <= 0 && bd <= 0){
			break;
		}

		if(sd >= ed && sd >= bd){
			r += st;
			s = 0;
			++t;
		} else if (ed >= bd) {
			r += et;
			e = 0;
			++t;
		} else {
			r += bl > 1 ? (bl - 1) : 1;
			b.pop_back();
			t += 2;
		}
	}

	cout << c - r << endl;
}

int main() {
	ios_base::sync_with_stdio(0);

	int tc;
	cin >> tc;

	for (int i = 0; i < tc; ++i) {
		solve(i);
	}

	return 0;
}