#include <iostream>
#include <vector>
#include <algorithm>
#include <cstring>
#include <set>
#include <unordered_set>
#include <map>
#include <unordered_map>
#include <queue>
#include <bitset>

using namespace std;
using ll = long long;
const int N = 1e5 + 5;

int n, a[N];

void solve() {
  cin >> n;
  string s; cin >> s;
  for (int i = 0; i < n; i++) {
    a[i+1] = s[i] - '0';
  }

  int cnt = 0;
  for (int i = 1; i <= n; i++) {
    if (i & 1) {
      cnt += a[i];
      continue;
    }
    int t = 0;
    int idx = i-1;
    while (idx) {
      t += a[idx];
      idx -= idx & -idx;
    }

    // printf("i=%d t=%d\n", i, t);
    if (a[i] + t == 1) cnt++;
  }

  printf("%d\n", cnt);
}

int main() {
  ios::sync_with_stdio(false); cin.tie(0);

  int t; cin >> t; while (t--)
    solve();

  return 0;  
}