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#include <algorithm>
#include <map>
#include <cstdio>

using namespace std;

void reduce(map<int, int>* prev, map<int, int>* next, int delta) {
  for(auto it = prev->begin(); it != prev->end(); it++) {
    if((it->first) > delta) {
      (*next)[(it->first) - delta] = it->second;
    }
  }
}

struct State {
  map<int, int>* ones;
  map<int, int>* twos;

  State():
    ones(new map<int, int>),
    twos(new map<int, int>) {}

  State(char* a, int n): State() {
    int start = 0;
    for(int i=1;i<n;i++) {
      if((a[i] == '1') && (a[i-1] != '1')) {
        if(start == 0) {
          (*ones)[i]++;
        } else {
          (*twos)[i-start]++;
        }
      } else if((a[i] != '1') && (a[i-1] == '1')) {
        start = i;
      }
    }
    if(a[n-1] != '1') {
      (*ones)[n-start]++;
    }
  }

  int countOnes() {
    int res = 0;
    for(auto it = ones->begin();it != ones->end();it++) {
      res += it->second;
    }
    return res;
  }

  State* withoutOne(int k) {
    State* next = new State();
    map<int, int>* newOnes = new map<int, int>;
    map<int, int>* newTwos = new map<int, int>;
    reduce(ones, newOnes, 1);
    if((*(newOnes))[k-1] > 1) {
      (*(newOnes))[k-1]--;
    } else {
      newOnes->erase(k-1);
    }
    reduce(twos, newTwos, 2);
    next->ones = newOnes;
    next->twos = newTwos;
    return next;
  }
};

pair<int, int> countZeros(int start, int t) {
  int remaining = start - t;
  if(remaining > 0) {
    return make_pair(remaining, 1);
  }
  return make_pair(0, 0);
}

pair<int, int> countZeros2(int start, int t) {
  int remaining = start - t;
  if((remaining == 1) || (remaining == 2)) {
    return make_pair(1, 1);
  } else if(remaining > 2) {
    return make_pair(remaining - 1, 2);
  }
  return make_pair(0, 0);
}

void dec(map<int, int>& m, int k) {
  if(m[k] > 1) {
    m[k]--;
  } else {
    m.erase(k);
  }
}

int solveStep(State* state) {
  int zeros = 0;
  int t = 0;
  map<int, int> ones(*(state->ones));
  map<int, int> twos(*(state->twos));
  while((!ones.empty()) || (!twos.empty())) {
    int last1 = -1;
    int last2 = -1;
    pair<int, int> s1;
    pair<int, int> s2;
    if(!ones.empty()) {
      last1 = ones.rbegin()->first;
      s1 = countZeros(last1, t);
    }
    if(!twos.empty()) {
      last2 = twos.rbegin()->first;
      s2 = countZeros2(last2, 2*t);
    }
    if((last1 >= 0) && (last2 >= 0)) {
      if(s1.first >= s2.first) {
        last2 = -1;
      } else {
        last1 = -1;
      }
    }
    if(last1 >= 0) {
      dec(ones, last1);
      zeros += s1.first;
      t += s1.second;
    } else {
      dec(twos, last2);
      zeros += s2.first;
      t += s2.second;
    }
  }
  return zeros;
}

int solve(State* state) {
  int full = solveStep(state);
  if(state->countOnes() <= 1) {
    return full;
  }
  int k = state->ones->rbegin()->first;
  State* r = state->withoutOne(k);
  int withoutOne = k + solveStep(r);
  delete r;
  return max(full, withoutOne);
}

int solve(char* a, int n) {
  bool oneExists = false;
  for(int i=0;i<n;i++) {
    if(a[i] == '1') {
      oneExists = true;
      break;
    }
  }
  if(!oneExists) {
    return 0;
  }
  State* state = new State(a, n);
  int res = n - solve(state);
  delete state;
  return res;
}

int main(int argc, char** argv) {
  int t, n;
  char a[100005];
  scanf("%d", &t);
  for(int i=0;i<t;i++) {
    scanf("%d", &n);
    while(true) {
      char c = getchar();
      if((c >= '0') && (c <= '1')) {
        a[0] = c;
        break;
      }
    }
    for(int j=1;j<n;j++) {
      a[j] = getchar();
    }
    int res = solve(a, n);
    printf("%d\n", res);
  }
  return 0;
}