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#include <bits/stdc++.h>
using namespace std;
#define fi first
#define se second
#define pb push_back
#define all(x) (x).begin(), (x).end()
#define mid (l+r)/2
#define PI acos((ld)-1)
#define BOOST ios_base::sync_with_stdio(0), cin.tie(0), cout.tie(0)
typedef long long ll;
typedef long double ld;
typedef pair<int, int> ii;
typedef vector<int> vi;
typedef vector<ll> vll;
typedef vector<ii> vii;
typedef vector<vi> vvi;

void solve(){
	int n;
	string s;
	cin >> n >> s;
	int zero = 0, one = 0;
	bool be = 0;
	vector<int> t;
	for(int i=0; i<n; i++){
		if(s[i] == '0'){
			zero++;
			if(i == n-1){
				if(be)
					t.pb(zero);
				continue;
			}
			if(s[i+1] == '1'){
				if(be)
					t.pb(zero/2), t.pb((zero+1)/2);
				else
					t.pb(zero);
			}
		}
		if(s[i] == '1'){
			one++;
			be = 1;
			zero = 0;
		}
	}
	sort(all(t), greater<int>());
	for(int i=0; i<t.size(); i++){
		one += min(t[i], i);
	}
	cout << one << "\n";
}

int main(){
	BOOST;
	int q;
	cin >> q;
	while(q--)
		solve();
}