// MagicDark
#include <bits/stdc++.h>
#define debug cerr << "[" << __LINE__ << "] "
#define SZ(x) (int) x.size() - 1
#define all(x) x.begin(), x.end()
#define ms(x, y) memset(x, y, sizeof x)
#define F(i, x, y) for (int i = (x); i <= (y); i++)
#define DF(i, x, y) for (int i = (x); i >= (y); i--)
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
template <typename T> inline void chkmax(T &x, T y) {x = max(x, y);}
template <typename T> inline void chkmin(T &x, T y) {x = min(x, y);}
template <typename T> inline void read(T &x) {
	x = 0; int f = 1; char c = getchar();
	for (; !isdigit(c); c = getchar()) if (c == '-') f = -f;
	for (; isdigit(c); c = getchar()) x = (x << 1) + (x << 3) + (c ^ 48);
	x *= f;
}
const int N = 1e5 + 10;
int n, ans, t0[N], t1[N];//, t[N];
// vector <int> v[N];
string st;
// void add(int x, int y) {
// 	for (; x <= n; x += x & -x) t[x] += y;
// }
// int query(int x) {
// 	int s = 0;
// 	for (; x; x -= x & -x) s += t[x];
// 	return s;
// }
void zhk() {
	ans = 0;
	cin >> n >> st; st = ' ' + st;
	F(i, 1, n) t0[i] = t1[i] = 0;
	F(i, 1, n) {
		int id = i + (i & -i);
		if (id <= n) {
			t0[id] += st[i] == '0';
			t1[id] += st[i] == '1';
		}
	}
	F(i, 1, n) {
		if (st[i] == '0') {
			if (t1[i] == 1) ans++;
		} else {
			if (t1[i] == 0) ans++;
		}
	}
	cout << ans << '\n';
	// int s = 0;
	// F(i, 1, n) t[i] = 0;
	// F(i, 1, n) {
	// 	if (st[i] == '0') {
	// 		if (t[i]) add(i, -t[i]), s++;
	// 	} else {
	// 		if (!t[i]) add(i, 1), s++;
	// 	}
	// 	// F(j, 1, n) cout << t[j] << ' '; cout << '\n';
	// }
	// cout << s << '\n';
}
signed main() {
	cin.tie(0) -> sync_with_stdio(0);
	int _ = 1;
	cin >> _;
	while (_--) zhk();
	return 0;
}
/* why?
*/