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#include <bits/stdc++.h>
 
#define st first
#define nd second
#define pb push_back
#define BOOST ios_base::sync_with_stdio(0); cout.tie(0); cin.tie(0);
#define PI 3.14159265359
 
using namespace std;
 
typedef long long ll;
constexpr ll MOD = 1000000007, sup = 29;
constexpr ll MOD_1 = 1234567891, sup_1 = 1009;
constexpr ll MOD_2 = 1000000009, sup_2 = 107;
constexpr int MXN = 100000+10, CZAPA = (1<<19)/*, INF = 1000000000*/;
constexpr ll INF = 1000000000000000000;

priority_queue<int> A, B;

int main(){
	BOOST;
	
	int queries;
	cin>> queries;
	while(queries--){
		while(!A.empty()) A.pop();
		while(!B.empty()) B.pop();
		int n;
		string s;
		cin>> n >> s;
		bool cool = true;
		for(char i : s){
			if(i == '1'){
				cool = false;
				break;
			}
		}
		if(cool){
			cout<< 0 << '\n';
			continue;
		}
		for(int i=0; i<n; i++){
			if(s[i] == '1') continue;
			int j = i;
			while(j+1 < n && s[j+1] == '0') j++;
			if(i == 0 || j == n-1){
				B.push(j-i+1);
			}
			else{
				A.push(j-i+1);
			}
		}
		int ans = 0, t = 0;
		while(!A.empty() && !B.empty()){
			int a = 0, b = 0;
			if(!A.empty()){
				a = A.top();
			}
			if(!B.empty()){
				b = B.top();
			}
			a -= 2*t;
			b -= t;
			if(a <= 0 && b <= 0) break;
			//cout<< a << ' ' << b << ' ';
			if(a > b){
				//cout<< "A\n";
				a += t-1;
				ans++;
				A.pop();
				B.push(a);
				b += t;
			}
			else{
				//cout<< "B\n";
				B.pop();
				ans += b;
			}
			t++;
		}
		cout<< n-ans << '\n';
	}
	
	


	return 0;
}