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//Jakub Rozek
//Pandemia
//czas: sumn*log(sumn)
//pammiec: n

#include "bits/stdc++.h"
using namespace std;

int test,n,x,wyn,p;
bool f; 
string s;
priority_queue <int> a,b;

void zmiennaque()
{
    while(!a.empty()) a.pop();
    while(!b.empty()) b.pop();
    x=0;
    f=0;

    for(int i=0; i<n; ++i)
    {
        if(s[i]=='1')
        {
            if(f)
            {
                if(x) b.push(x);
            }
            else
            {
                a.push(x);
                f=1;
            }
            x=0;
        }
        else ++x;
    }
    a.push(x);
}

void  usuna()
{
    p=a.top()-x;
    a.pop();
    if(p<=0) return;
    wyn+=p;
    ++x;
}
void usunb()
{
    p=b.top()-2*x;
    b.pop();
    if(p<=0) return;
    wyn+=1;
    p-=1;
    a.push(p+x);
    ++x;
}

void solution()
{
    cin>>n>>s;

    zmiennaque();

    if(a.size()==1)
    {
        cout<<"0\n";
        return;
    }

    x=0;
    wyn=0;
    while(!a.empty() || !b.empty())
    {
        if(a.empty()) usunb();
        else if(b.empty()) usuna();
        else
        {
            if(a.top()*2>=b.top()) usuna();
            else usunb();
        }
    }

    cout<<n-wyn<<"\n";
    return;
}

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

    cin>>test;
    while(test--) solution();

    return 0;
}