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

typedef long long ll;

const int N = 2e5 + 5;

int T, n, ans, pre[N], suf[N];

string s;

inline void solve() {
	cin >> n >> s;
	s = "#" + s;
	for (int i = 1; i <= n; ++i) {
		pre[i] = pre[i - 1] + (s[i] == '1');
	}
	for (int i = n; i; --i) {
		suf[i] = suf[i + 1] + (s[i] == '1');
	}
	if (s[1] == '0' || s[n] == '0') {
		cout << pre[n] << "\n";
		return;
	}
	for (int i = 1; i < n; ++i) {
		if (s[i] == '0' && s[i + 1] == '0') {
			cout << pre[n] << "\n";
			return;
		}
	}
	ans = 1e9;
	for (int i = 1; i <= n; ++i) {
		if (s[i] == '0') {
			ans = min(ans, (pre[i] << 1) + suf[i]);
			ans = min(ans, (suf[i] << 1) + pre[i]);
		}
	}
	cout << ans << "\n";
}

int main() {
	#ifdef LOCAL
		assert(freopen("test.in", "r", stdin));
		assert(freopen("test.out", "w", stdout));
	#endif
	ios::sync_with_stdio(false); cin.tie(nullptr); cout.tie(nullptr);
	cin >> T;
	while (T--) {
		solve();
	}
	return 0;
}