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#include <stdio.h>
#include <time.h>
#include <math.h>
#include <stdlib.h>
#include <string.h>
#include <map> 
#include <string>
#include <vector>  
#include <iostream> 
#include <sstream> 
#include <queue>
#include <algorithm>
#include <assert.h>


using namespace std;

#define ll long long
#define PB 		push_back
#define FOR(a,start,end) 	for(int a=int(start); a<int(end); a++)
#define INF 		INT_MAX
#define SORT(a) 	sort(a.begin(),a.end()) 
#define CL(a,x) 		memset(a,x,sizeof(a))
#define REP(a,x)	for(int a=0;a<x;a++)
#define REP1(a,x)	for(int a=1;a<=x;a++)
#define MP 		make_pair



typedef vector<ll>     vi;
typedef pair<ll, ll>     pii;
typedef vector<string> vs;
typedef vector<pii> vii;
typedef vector<vector<ll> > vvi;
typedef vector<vector<string> > vvs;
typedef vector<pair<string, string> > vss;
typedef pair<string, string> pss;
typedef pair<ll, pii> ppii;
typedef vector<ppii> vppii;
typedef vector<vector<pii> > vvii;
typedef vector<vvi> vvvi;


ll n, k, a, b, c, z, m, d, t;
vi va,vk;
string w;
priority_queue<vi> pq;
int main() {
	//freopen("c:\\wojtek\\uva\\pa\\debug\\t1.in.txt", "rt", stdin);

	cin >> t;
	for (int cas = 1; cas <= t; cas++) {
		cin >> n;
		cin >> w;
		va.clear();
		vk.assign(2, 0);
		while (!pq.empty())
			pq.pop();
		d = 0;
		k = 0;
		c = w[0]-'0';
		if (c == 0)
			d = 1;
		for (int i = 1; i < n; i++) {
			if (w[i] == '0') {
				if (c == 1) {
					c = 0;
					k = 1;
				}
				d++;
			}
			else {
				if (c == 0) {
					c = 1;
					k++;
					vk[0] = d*(3-k);
					vk[1] = k;
					pq.push(vk);
					d = 0;
					k = 0;
				}
			}
		}
		if (d > 0) {
			vk[0] = 2*d;
			vk[1] = 1;
			pq.push(vk);
		}
		d = 0;
		z = 0;
		while (!pq.empty()) {
			vk = pq.top();
			pq.pop();
			if (vk[1] > 1) {
				vk[0] -= 2 * d;
				if (vk[0] > 0) {
					vk[1]--;
					z++;
					vk[0]--;
					vk[0] += d;
					vk[0] *= 2;
					pq.push(vk);
				}
				else
					break;
			}
			else {
				if (vk[0]/2 > d)
					z += vk[0]/2 - d;
				else
					break;
			}
			d++;
		}
		cout << n - z << endl;
	}

	return 0;

}