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#include <iostream>
#include <vector>
#include <algorithm>
#include <functional>
#include <iterator>
#include <bitset>
#include <string>
#include <utility>

void splitToScetors(std::vector<std::pair<int,bool> > &sectors, const std::string& s)
{

    int len=0;
    bool start = true;
    for(const auto& x:s)
    {
        if(x=='1')
        {
            if(len) sectors.push_back({len, start});
            start = false;
            len = 0;
        }
        else
        {
            ++len;
        }
    }
    if(len) sectors.push_back({len, true});
}

int calculateNumberOfOK(std::vector<std::pair<int,bool> > &sectors)
{

    std::sort(sectors.begin(), sectors.end(), [](const std::pair<int,bool> &a, const std::pair<int,bool> &b) -> bool
             { int prioA = a.second? 2*a.first:a.first;
               int prioB = b.second? 2*b.first:b.first;
               return prioA > prioB;
             });
    int safe =0, t=0;
    for(const auto& x:sectors)
    {
        if(x.first < t) break;
        if(x.second)
        {
            if(x.first > t) safe += x.first -t;
            t++;
        }
        else
        {
            if(x.first -2*t ==1) ++safe;
            else if(x.first > (2*t +1)) safe += x.first -2*t-1;
            t++;
            t++;
        }
    }
    return safe;
}
int main()
{
    std::ios_base::sync_with_stdio(false);
    long long int t;
    std::cin>>t;
    for(int i=0; i<t; ++i)
    {
       long long int n;
       std::string s;
       std::cin>>n>>s;
       std::vector<std::pair<int,bool>> sectors;
       splitToScetors(sectors, s);
       int numb = n - calculateNumberOfOK(sectors);
       std::cout << numb <<std::endl;
    }
    return 0;
}