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#include <iostream>
#include <queue>
#include <algorithm>
using namespace std;

typedef long long ll;
priority_queue<pair<ll, bool>> Q; //rozmiar pola i rodzaj 1 lub 2

void task(ll n, string s) {
	ll p = 0;
	ll ans = 1;
	while (s[p] == '0' && p < n) p++;
	if (p > 0) Q.push({ 2*p, 0 });
	if (p == n) {
		cout << 0;
		return;
	}
	ll r = 0;
	for (ll i = p + 1; i < n; i++) {
		if (s[i] == '1') {
			ans++;
			if (r > 0) Q.push({ r, 1 });
			r = 0;
		}
		else r++;
	}
	if (r > 0) Q.push({ 2*r, 0 });
	ll k = 0; 
	while (!Q.empty()) {
		pair<ll, bool>v = Q.top();
		Q.pop();
		if (v.second == 0) {
			ans += min(v.first/2, k);
		}
		else {
			ll akt = 0;
			if (k <= (v.first + 1) / 2) {
				akt += 2 * k;
				if (v.first % 2 == 1 && akt > 0)
					akt--;
				ans += akt;
				v.first -= (akt + 1);
				v.first *= 2;
				v.second = 0;
				if(v.first > 0)
				Q.push(v);
			}
			else ans += v.first;
		}
		k++;
	}
	cout << ans << "\n";
}

int main()
{
	ios_base::sync_with_stdio(0);
	cin.tie(0);
	cout.tie(0);
	ll t, n;
	string s;
	cin >> t;
	for (ll i = 0; i < t; i++) {
		cin >> n >> s;
		task(n, s);
	}
}