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

using namespace std;

typedef long long int LL;
typedef vector<LL> VL;
typedef vector<VL> VVL;
#define FOR(x, b, e) for(int x = b; x < (e); ++x)
#define REP(x, n) for(int x = 0; x < (n); ++x)
#define EACH(x, y) for(auto &(x) : y)
#define ALL(c) (c).begin(), (c).end()
#define SIZE(x) ((int)(x).size())
#define PB push_back

struct City {
	LL start;
	LL end;
	LL duration;
	bool oneWay = false;

	bool operator< (const City& other) const {
		if(duration != other.duration)
			return duration > other.duration;
		else
			return oneWay > other.oneWay;
	}
};

// firstly get all the intervals, sorted in descending order, get the biggest ones, make borders with vaccinated cities
// do as long as there are any left, check how many are unvaccinated, this is the result
int solve(string &s) {
	vector<City> vc;

	LL len = 0;
	City city;
	REP(i, SIZE(s)) {
		if (s[i] == '0') {
			if (!len) {
				city.start = i;
				if (i == 0) city.oneWay = true;
			}

			len++;
		}
		if (s[i] == '1' || i + 1 == SIZE(s)) {
			if (len) {
				i + 1 == SIZE(s) ? city.end = i : city.end = i - 1;
				city.duration = len;

				if (i + 1 == SIZE(s)) city.oneWay = true;

				vc.PB(city);

				city.start = 0;
				city.end = 0;
				city.duration = 0;
				city.oneWay = false;
			}

			len = 0;
		}
	}

	sort(ALL(vc));

	LL healthy = 0, dayPenalty = 0;

	EACH(item, vc) {
		if ((item.oneWay ? item.duration - (dayPenalty / 2) : item.duration - dayPenalty - 1) <= 0) break;
		
		if (item.oneWay) healthy += item.duration - (dayPenalty / 2);
		else healthy += item.duration - dayPenalty - 1;
		dayPenalty += 2;
	}

	return SIZE(s) - healthy;
}

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

	int n, t;
	cin >> t;

	REP(i, t) {
		cin >> n;

		string s;
		VL vec;
		cin >> s;

		LL ans = solve(s);
		cout << ans << '\n';
	}

	return 0;
}