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#include <iostream>
#include <vector>
#include <algorithm>
#include <array>
//#include <map>
#include <math.h>
#include <map>
// #include <bits/stdc++.h>

using namespace std;

long zarazonych;
string ch;

struct greater2
{
    template<class T>
    bool operator()(T const &a, T const &b) const { return a > b; }
};

void print_v(vector<array<long, 3> > vect)
{

    for (array<long, 3> i : vect) {
        for (auto x : i)
            cout << x << " ";
        cout << endl;
    }
}


long ile_zarazonych(string miasta) {
  long a = 0;
  long size = miasta.size();
  vector<array<long, 3> > niezarazone;

  zarazonych = 0;

  long max = 0;
  long dl = 0;


  for (long i = 1; i < size; ++i) {

    if (miasta[i] == '1') zarazonych++;
    if (miasta[i] == '1' && miasta[i - 1] == '0' ) {
      //koniec ciagu wolnych miast
      // cout << "a: " << a << " dl: " << i - a << "\n";
      // int c;
      dl = i - a;
      if (a == 0) {
        // poczatkowe
        niezarazone.push_back({dl * 2, dl, -1});
      } else {
        // if (max < dl) {
        //   max = dl;
        // }
        niezarazone.push_back({dl, dl, -2});
      }

    } else if (miasta[i] == '0' && miasta[i - 1] == '1' ) {
      a = i;
    }
  }
  if (miasta[size - 1] == '0') {
    // cout << "a2: " << a << " dl size: " << size - a << "\n";
    dl = size - a;
    niezarazone.push_back({dl * 2, dl, -1});
  }

  sort(niezarazone.begin(), niezarazone.end(), greater2());

  // print_v(niezarazone);
  // cout << "zarazonych: " << zarazonych << "\n";

  long kum = 0;
  long miasta_ocalone = 0;
  long ogniska;
  long suma_ocalonych = 0;
  for (long i = 0; i < niezarazone.size(); ++i) {
    // miasta_ocalone = niezarazone[i][0] - kum;
    ogniska = -niezarazone[i][2];
    long m = niezarazone[i][1];
    if (ogniska == 1) {
      miasta_ocalone =  m - kum;
      if (miasta_ocalone > 0) {
        kum += 1;
      }
    } else if (ogniska == 2) {
      miasta_ocalone = m - kum * 2;
      if (miasta_ocalone > 1) {
        miasta_ocalone -= 1;
      }
      if (miasta_ocalone > 1) {
        kum += 2;
      } else if (miasta_ocalone > 0) {
        kum += 1;
      }
    }

    if (miasta_ocalone > 0) suma_ocalonych += miasta_ocalone;


    // cout << "i: " << i << " m:" << m << " miasta_ocalone: " << miasta_ocalone << " ogniska: " << ogniska << " kum out: " << kum << " suma_ocalonych: " << suma_ocalonych << "\n";


  }

  // cout << "suma_ocalonych: " << suma_ocalonych << " size: " << size << "\n";

  return size - suma_ocalonych;
}

int main() {
  long t;
  cin >> t;
  long n;
  string miasta;

  long wynik;



  for (long i = 0; i < t; i++) {
    cin >> n;
    cin >> miasta;
    // cout << "\nn: " << n << " miasta: " << miasta << "\n";
    wynik = ile_zarazonych(miasta);
    // cout << "WWWWW --- zarazonych wynik: " << wynik << "\n";
    cout << wynik << "\n";
  }

  //cout << "sprawdzam wynik:" << suma_slowa(wynik) << "\n";

}