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#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp> // Common file
#include <ext/pb_ds/tree_policy.hpp> // Including tree_order_statistics_node_update

using namespace std;
using namespace __gnu_pbds;

typedef tree<int, null_type, less<int>, rb_tree_tag, tree_order_statistics_node_update>
ordered_set;	

struct splitmix64_hash {
	static uint64_t splitmix64(uint64_t x) {
		// http://xorshift.di.unimi.it/splitmix64.c
		x += 0x9e3779b97f4a7c15;
		x = (x ^ (x >> 30)) * 0xbf58476d1ce4e5b9;
		x = (x ^ (x >> 27)) * 0x94d049bb133111eb;
		return x ^ (x >> 31);
	}
 
	size_t operator()(uint64_t x) const {
		static const uint64_t FIXED_RANDOM = std::chrono::steady_clock::now().time_since_epoch().count();
		return splitmix64(x + FIXED_RANDOM);
	}
};
 
template <typename K, typename V, typename Hash = splitmix64_hash>
using hash_map = __gnu_pbds::gp_hash_table<K, V, Hash>;
 
template <typename K, typename Hash = splitmix64_hash>
using hash_set = hash_map<K, __gnu_pbds::null_type, Hash>;

template<class A,class B>auto&operator<<(ostream&o,pair<A,B>p){return o<<'('<<p.first<<", "<<p.second<<')';}
template<class T>auto operator<<(ostream&o,T x)->decltype(x.end(),o){o<<'{';int i=0;for(auto e:x)o<<", "+2*!i++<<e;return o<<'}';}
#ifdef DEBUG
#define debug(x...) cerr<<"["#x"]: ",[](auto...a){((cerr<<a<<"; "),...);}(x),cerr<<'\n'
#else
#define debug(...) {}
#endif

#define FOR(i,a,b) for(int i = (a); i <= (b); ++i)
#define FORD(i,a,b) for(int i = (a); i >= (b); --i)
#define RI(i,n) FOR(i,1,(n))
#define REP(i,n) FOR(i,0,(n)-1)
#define mini(a,b) a=min(a,b)
#define maxi(a,b) a=max(a,b)
#define pb push_back
#define st first
#define nd second
#define sz(w) (int) w.size()
typedef vector<int> vi;
typedef long long ll;
typedef long double ld;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
typedef pair<pii, int> para;
const ll inf = 1e18 + 7;
const ll maxN = 1e6 + 5;
const ll MOD = 1e9 + 7;

// sprawdz MODULO!
int main() {
    mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
	ios_base::sync_with_stdio(0);
	cin.tie(0); cout.tie(0);
	int t; cin >> t;
	REP(_, t) {
		int n; cin >> n;
		string s; cin >> s;
		int prvOne = -1;
		multiset<int, greater<int>> nums;
		int first = 0, last = 0;
		REP(i, n) {
			if (s[i] == '1') {
				if (prvOne != -1) {
					if (i - prvOne > 1) {
						nums.insert(i - prvOne - 1);
					}
				} else {
					first = i - prvOne - 1;
				}
				prvOne = i;
			}
		}
		last = n - prvOne - 1;
		if (first > last) swap(first, last);
		debug(nums, last, first);
		int diff = 0, ans = 0;
		while (!nums.empty()) {
			int x = *nums.begin(); nums.erase(nums.begin());
			x -= diff;
			int check = last;
			if (last == 0) {
				check = first;
			}
			if (x - 2 <= check - 1 && check > 0) {
				if (last > 0) {
					last = 0;
					first--;
					first = max(first, 0);
				} else {
					first = 0;
				}
				ans += check;
				diff += 2;
				nums.insert(x);
			} else {
				if (x > 1) {
					ans += (x - 1);
					diff += 4;
					last -= 2;
					first -= 2;
					last = max(last, 0);
					first = max(first, 0);
				} else if (x == 1) {
					ans++;
					first--;
					last--;
					diff += 2;
					last = max(last, 0);
					first = max(first, 0);
				}
			}
			debug(ans, diff, first, last);
		}
		debug(last, first);
		if (last > 0) {
			if (first > 0) {
				ans += max(last + first - 1, 0);
			} else {
				ans += max(last, 0);
			}
		} else {
			ans += max(first, 0);
		}
		cout << n - ans << endl;
	}
	return 0;
}