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#include <stdio.h>
#include <vector>
#include <map>
#include <unordered_set>
#include <queue>
#include <set>
#include <unordered_map>
#include <math.h>
#include <limits.h>
#include <algorithm>
#include <functional>
#include <iterator>
#include <algorithm>
#include <string>
#include <iostream>

using namespace std;

#define pb push_back
#define mp make_pair

typedef long long ll;
typedef unsigned long long ull;

using namespace std;


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

  int t, n;
  char ci;

  cin >> t;

  while (t --> 0) {
    vector<bool> cities;
    vector<int> strikes;
    int toxic = 0;
    cin >> n;
    int no_toxic_strike = 0;
    int left = -1;
    for (int i=0; i<n; ++i) {
      cin >> ci;
      bool is_toxic = ci == '1';
      cities.pb(is_toxic);
      if (is_toxic) {
        toxic++;
        if (left == -1) {
          left = no_toxic_strike;
        } else {
          if (no_toxic_strike > 0) strikes.pb(no_toxic_strike);
        }
        no_toxic_strike = 0;
      } else {
        no_toxic_strike++;
      }
    }
    int right = no_toxic_strike;
    vector<int> singles;
    singles.pb(left);
    singles.pb(right);

    sort(strikes.begin(), strikes.end());
    sort(singles.begin(), singles.end());

    int saved = 0;
    int ticks = 0;
    int old_ticks = -1;
    while (old_ticks != ticks) {
      old_ticks = ticks;
      int mcurrent = -1;
      if (strikes.size() > 0) mcurrent = strikes.back() - ticks * 2;
      int scurrent = -1;
      if (singles.size() > 0) scurrent = singles.back() - ticks;

      if (scurrent < 1 && mcurrent < 1) break;

      if (scurrent > 0 && (scurrent >= mcurrent - 1 || mcurrent == 3 || (mcurrent == 5 && scurrent == 3))) {
        saved += scurrent;
        ticks++;
        singles.pop_back();
      } else if (mcurrent > 0) {
        if (mcurrent > 2) {
          ticks += 2;
          saved += mcurrent-1;
          strikes.pop_back();
        } else if (mcurrent == 2 || mcurrent == 1) {
          ticks++;
          saved += 1;
          strikes.pop_back();
        }
      } else if (scurrent > 0) {
        saved += scurrent;
        ticks++;
        singles.pop_back();
      }
    }

    cout << (n - saved) << endl;
  }

  return 0;
}