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#include<bits/stdc++.h>
#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 PB push_back
#define EB emplace_back
#define FI first
#define SE second
#define umap unordered_map
#define uset unordered_set
#define vi vector<int>
#define vvi vector<vi>
#define vll vector<ll>
#define vvll vector<vll>
#define vpii vector<pii>
#define pii pair<int, int>
#define pll pair<ll, ll>
#define ALL(X) (X).begin(),(X).end()
#ifndef DEBUG
#define endl (char)10
#endif
using namespace std;
using ll = long long;
using ld = long double;

template <class T>
istream& operator>> (istream& is, vector<T>& vec){
    FOR(i,0,vec.size()) is >> vec[i];
    return is;
}
template <class T>
ostream& operator<< (ostream& os, vector<T>& vec){
    for(auto& t : vec) os << t << " ";
    return os;
}

void st() {
    int n; string s;
    cin >> n >> s;
    int pocz = 0;
    while(pocz < n && s[pocz] == '0') pocz++;
    if (pocz == n){
        cout << 0 << endl;
        return;
    }
    priority_queue<int> J, D;
    if (pocz > 0) J.push(pocz);
    int kon = n - 1;
    while(s[kon] == '0') kon--;
    if (kon < n - 1) J.push(n - 1 - kon);
    int ile = 0;
    kon++;
    FOR(i,pocz,kon){
        if (s[i] == '1' && ile != 0){
            D.push(ile);
            ile = 0;
        }
        if (s[i] == '0') ile++;
    }
    int ocal = 0;
    int step = 0;
    while(J.size() > 0 || D.size() > 0){
        bool pickD = false;
        if (J.size() == 0) pickD = true;
        else if (D.size() == 0) pickD = false;
        else {
            //cout << D.top() - step - (int) J.size() - (int) D.size() << endl;
            if (D.top() - step - (int) J.size() > J.top()) pickD = true;
        }

        if (pickD){
            int x = D.top();
            //cout << "Front d = " << x << endl;
            D.pop();
            if (x - step * 2 > 0){
                //cout << "Saved 1 from D. Push " << x - step - 1 << " cause got " << x << endl;
                ocal++;
                step++;
                J.push(x - step);
            }
        } else {
            int x = J.top();
            J.pop();
            if (x - step > 0){
                //cout << "Saved " << x - step << " from J" << endl;
                ocal += x - step;
                step++;
            }
        }
    }
    cout << n - ocal << endl;
}

int main () {
    ios_base::sync_with_stdio(false);
    cin.tie(0);
    int t;
    cin >> t;
    FOR(i,0,t){
        if (t < 50){
            cerr << "-------------------" << endl;
        }
        //cout << "Case #" << i + 1 <<": ";
        st();
    }
}