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

#ifdef LOCAL
template<class T, class U>
ostream& operator<<(ostream& os, pair<T, U> p) {
    return os << "(" << p.first << ", " << p.second << ")";
}

template<class C, class = typename C::value_type>
typename enable_if<!is_same<C, string>::value, ostream&>::type
operator<<(ostream& os, C c) {
    for (auto i = c.begin(); i != c.end(); i++) {
        os << " {"[i == c.begin()] << *i << ",}"[next(i) == c.end()];
    }
    return os;
}

#define debug(x) { cerr << #x << " = " << x << endl; }
#else
#define debug(...) {}
#endif

void build(const string &s, vector<int> &two, queue<int> &one) {
  int group = 0;
  bool first = true;

  vector<int> tmp;

  for (char c : s) {
    if (c == '1') {
      if (group > 0) {
        if (first) {
          tmp.push_back(group);
        }
        else {
          two.push_back(group);
        }
      }
      group = 0;
      first = false;
    }
    else {
      group++;
    }
  }
  if (group > 0) {
    tmp.push_back(group);
  }

  sort(tmp.begin(), tmp.end(), greater<int>());
  for (int x : tmp) {
    one.push(x);
  }
}

int solve(int n, string s) {
  int count_ones = count(s.begin(), s.end(), '1');
  if (count_ones == 0) {
    return 0;
  }
  
  vector<int> two;
  queue<int> one;
  build(s, two, one);

  sort(two.begin(), two.end());

  int t = 0;
  int next_two = int(two.size()) - 1;
  int res = 0;

  while (next_two >= 0 || !one.empty()) {
    debug("STEP");

    while (!one.empty() 
        && (one.front() - t <= 0 
            || (one.front() - t == 1 
                && (one.size() >= 2 || (next_two >= 0 && two[next_two] - 2 * t > 0))))) {
      one.pop();
    }

    if (!one.empty()) {
      debug("one");
      debug(one.front() - t);
      res += one.front() - t;
      one.pop();
    }
    else {
      debug("two");
      if (next_two < 0) {
        break;
      }

      int g = two[next_two];
      next_two--;

      if (g - 2 * t <= 0) {
        break;
      }
      res++;
      debug(res);
      if (g - 2 * t >= 3) {
        debug(g - t - 1);
        one.push(g - t - 1);
      }
    }

    t++;
  }

  return n - res;
}

int main() {
  ios_base::sync_with_stdio(false);

  int t;
  cin >> t;

  while (t--) {
    int n;
    string s;
    cin >> n >> s;

    cout << solve(n, s) << "\n";
  }
}