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#include <cstdio>
#include <vector>
#include <string>
#include <algorithm>
using namespace std;

char s[101013];

int tcase() {
	int n;
	scanf("%d %s", &n, s);
	int pop = -1;
	vector<int> je(1), dw(1);
	for (int i = 0; i < n; i++) {
		if(s[i] == '1') {
			if (pop == -1) {
				je.push_back(i);
			} else {
				dw.push_back(i - 1 - pop);
			}
			pop = i;
		}
	}
	je.push_back(n-1-pop);
	sort(je.begin(), je.end());
	sort(dw.begin(), dw.end());
	int t = 0, res = 0;
	while(je.back() > t || dw.back() > t+t) {
		if (je.back() * 2 >= dw.back()) {
			res += je.back() - t;
			t++;
			je.pop_back();
		} else if (dw.back() - t - t == 1) {
			res++;
			t++;
			dw.pop_back();
		} else {
			res += dw.back() - t-t-1;
			t += 2;
			dw.pop_back();
		}
	}
	return n-res;
}

int main() {
	int tt;
	scanf("%d", &tt);
	while(tt--) {
		printf("%d\n",tcase());
	}
	return 0;
}