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#include<bits/stdc++.h>

using namespace std;

constexpr int MAX_N = 100000;

char s[MAX_N+9];
vector<int> v;

void solve() {
	int n;
	scanf("%d", &n);
	scanf("%s", s);
	v.clear();
	
	int l = 0;
	int p = n-1;
	while(s[l] == '0' && l < n) {
		++l;
	}
	if(l >= n) {
		printf("0\n");
		return;
	}
	while(s[p] == '0') {
		--p;
	}
	
	int i = l;
	while(i < p) {
		if(s[i] == '1' ) {
			while(s[i] == '1') ++i;
		}
		else {
			int j = i;
			while(s[j] == '0') ++j;
			//printf("v.pb(%d)\n", j-i);
			v.push_back(j-i);
			i = j;
		}
	}
	p = n-p-1;
	//printf("l:%d\n", l);
	//printf("p:%d\n", p);
	
	sort(v.begin(), v.end());
	
	if(l < p) {
		swap(l,p);
	}
	int wyn = 0;
	i = 0;
	while(v.size()) {
		if(2*l > v.back()) {
			wyn += max(0, l-i);
			++i;
			l = 0;
		}
		if(2*p > v.back()) {
			wyn += max(0, p-i);
			++i;
			p = 0;
		}
		if(v.back() >= 2*i+3) {
			wyn += v.back()-2*i-1;
			i += 2;
		} else 
		if(v.back() > 2*i) {
			++wyn;
			++i;
		}
		else {
			break;
		}
		v.pop_back();
	}
	if(l > p) {
		wyn += max(0, l-i);
		++i;
		l = 0;
		wyn += max(0, p-i);
		++i;
		p = 0;
	}
	else {
		wyn += max(0, p-i);
		++i;
		p = 0;
		wyn += max(0, l-i);
		++i;
		l = 0;
	}
	
	printf("%d\n", n-wyn);
}

int main() {
	int T;
	scanf("%d", &T);
	while(T--) {
		solve();
	}
}

/*
1
1000
0000000000000000000000000000000000000000000000000000000000000000000000010000000000000000000000000000000000000000000000000000000000000000000000000000000000000010000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000001000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000010000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000001000000000000000000000000000000000000000000100000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000010000000000000000000000000000000000000000000000001000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000001000000000000000000

//*/