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// Grzegorz Ryn
// V LO Kraków

#include <bits/stdc++.h>

using namespace std;

typedef long long ll;
typedef long double ld;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
typedef vector<bool> vb;
typedef vector<int> vi;
typedef vector<vector<int>> vvi;
typedef vector<ll> vl;
typedef vector<vector<ll>> vvl;

#define pb push_back
#define eb emplace_back
#define mp make_pair
#define mt make_tuple
#define st first
#define nd second
#define FOR(__VAR, __START, __END) for(int __VAR=__START; __VAR<=__END; __VAR++)
#define FORB(__VAR, __START, __END) for(int __VAR=__START; __VAR>=__END; __VAR--)
#define FORK(__VAR, __START, __END, __DIFF) for(int __VAR=__START; __VAR<=END; __VAR+=__DIFF)
#define all(__VAR) (__VAR).begin(), (__VAR).end()
#define rall(__VAR) (__VAR).rbegin(), (__VAR).rend()
#define DEBUG(__VAR) cout << #__VAR << ": " << __VAR << endl;

template<typename __T1, typename __T2>
ostream & operator<<(ostream &out, pair<__T1, __T2> &__VAR) {
	cout << "[" << __VAR.st << ", " << __VAR.nd << "]";
	return out;
}

template<typename __T>
ostream & operator<<(ostream &out, vector<__T> &__VAR) {
	cout << "[";
	FOR(i, 0, (int)__VAR.size()-2)
		cout << __VAR[i] << ", ";
	if(__VAR.size()>0)
		cout << __VAR[__VAR.size()-1];
	cout << "]" << endl;
	
	return out;
}

const int INF=1e9;

int main() {
	ios_base::sync_with_stdio(0);
	cin.tie(0);
	cout.tie(0);
	
	int T;
	cin >> T;
	while(T--) {
		int N;
		cin >> N;
		string S;
		cin >> S;
		S += "#";
		vector<pii> seg;
		for(int i=0, prv = S[0], p=0; i<=N; i++) {
			if(S[i] != prv && prv == '0') {
				seg.pb({p, i-1});
			}
			if(S[i] != prv) {
				p = i;
				prv = S[i];
			}
		}
		
		vector<int> cnt(N+1,0), mid(N+1,0);
		int mx = 0;
		for(auto[p,q]:seg) {
			int len = q-p+1;
			mx = max(len, mx);
			if(p == 0 || q == (N-1)) {
				cnt[len]++;
			}
			else {
				cnt[len/2]+=2;
				if(len%2 == 1) {
					mid[len/2]++;
				}
			}
		}
		
		if(mx == 1) {
			cout << N-1 << '\n';
			continue;
		}
		
		int t = 0, result = 0;
		for(int len=N; len>0; len--) {
			int res = 0;
			while(cnt[len]--) {
				int l = len-t;
				if(l > 0) {
					t++;
					result += l;
					res++;
				}
			}
			int num = min(mid[len], res/2);
			result += num;
			mid[len] -= num;
			if(len-t == 0 && mid[len]>0) {
				t++;
				result++;
			}
		}
		cout << N-result << '\n';
	}

	return 0;
}