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

using namespace std;

#define MAXN 100000


void decrease_and_remove(list<int>* v, int decrement) {
	list<int>::iterator i = v->begin();
	while (i != v->end()) {
		*i = *i - decrement;
		if (*i <= 0) i = v->erase(i);
		else ++i;
	}
}

void print_list(list<int>* v) {
	for (list<int>::iterator i = v->begin(); i != v->end(); ++i) cout << *i << " ";
	cout << endl;
}

void policz() {
	int n;
	vector<int> v;
	cin >> n;

	for (int i = 0; i < n; i++) {
		char val;
		cin >> val;
		if (val == '1') v.push_back(1); else v.push_back(0); 
	}
	
	//for (int i = 0; i < n; ++i) {
	//	cout << v[i];
	//}
	
	int vaccined = 0;
	list<int> one_end;
	list<int> two_ends;
	
	int current_length = 0;
	int is_left_opened;
	if (v[0] == 0) is_left_opened = 1; else is_left_opened = 0;
	
	for (int i = 0; i < n; ++i) {
		if (v[i] == 0) current_length++;
		else {
			if (current_length > 0) {
				if (is_left_opened == 1) one_end.push_back(current_length);
				else two_ends.push_back(current_length);
				current_length = 0;
				is_left_opened = 0;
			}
		}
	}
	
	// All zeros
	if (current_length > 0 && is_left_opened) {
		cout << 0 << endl;
		return;
	}
	if (current_length > 0) one_end.push_back(current_length);
	
	//cout << "ONE END" << endl;
	//for (int i = 0; i < one_end.size(); ++i) cout << one_end[i];
	//cout << endl;
	
	
	//cout << "TWO ENDS" << endl;
	//for (int i = 0; i < two_ends.size(); ++i) cout << two_ends[i];
	//cout << endl;
	//cout << "=====================================" << endl;
	
	while (one_end.size() > 0 || two_ends.size() > 0) {
		//cout << "===================================================" << endl;
		//cout << "ITERATION " << endl;
		//cout << "ONE END "; print_list(&one_end);
		//cout << "TWO ENDS "; print_list(&two_ends);
		
		list<int>::iterator max_one;
		int max_one_value = 0;
		for (list<int>::iterator i = one_end.begin(); i != one_end.end(); ++i) { if (*i > max_one_value) { max_one_value = *i; max_one = i; }}
		list<int>::iterator max_two;
		int max_two_value = 0;
		for (list<int>::iterator i = two_ends.begin(); i != two_ends.end(); ++i) { if (*i > max_two_value) { max_two_value = *i; max_two = i; }}
		
		
		
		int variant = 0;
		if (max_one_value == 0) variant = 2;
		else if (max_two_value == 0) variant = 1;
		else if (max_two_value >= 2 * max_one_value + 1)
			variant = 2;
		else
			variant = 1;
		
		//cout << "MAX ONE " << max_one_value << " MAX TWO " << max_two_value << " VARIANT " << variant << endl;
		
		if (variant == 1) {
			//cout << "AAAAA 1" << endl;
			//list<int>::iterator max_one;
			//for (max_one = one_end.begin(); max_one != one_end.end(); ++max_one) {
			//	if (*max_one == max_one_value) break;
			//}
			//cout << "AAAAA 2" << endl;
			vaccined += max_one_value;
			//cout << "AAAAA 3" << endl;
			one_end.erase(max_one);
			//cout << "MAX ONE END " << max_one_value << endl;
		} else {
			//cout << "BBBBB 1" << endl;
			//for (list<int>::iterator max_two = two_ends.begin(); max_two != two_ends.end(); ++max_two) {
			//	if (*max_two == max_two_value) { two_ends.erase(max_two); break; };
			//}
			//cout << "BBBBB 2" << endl;
			vaccined += 1;
			two_ends.erase(max_two);
			//cout << "BBBBB 3" << endl;
			//two_ends.erase(max_two);
			//cout << "BBBBB 4" << endl;
			one_end.push_back(max_two_value - 1);
			//cout << "MAX TWO ENDS " << max_two_value << endl;
		}
		//cout << "CCCCC 1" << endl;
		decrease_and_remove(&one_end, 1);
		decrease_and_remove(&two_ends, 2);
		//cout << "ONE END "; print_list(&one_end);
		//cout << "TWO ENDS "; print_list(&two_ends);
		//cout << "VACCINED " << vaccined << endl;
	}
	
	cout << (n - vaccined) << endl;
	
}

int main()
{
	int t;
	cin >> t;
	
	for (int i = 0; i < t; ++i) policz();
}