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#include <iostream>
#include <vector>
#include <algorithm>
#include <map>
using namespace std;

int main() {
    std::ios::sync_with_stdio(false);
    cin.tie(NULL);
    int n,t;
    cin >> t;
    string s;
    while (t--)
    {
        cin >> n;
        cin >> s;
        //cout << n << ' ' << s << endl;
        int i=0;
        int c = 0;
        vector<pair<int,int>> v;
        while (i<n && s[i]=='0') {c++; i++;}
        if (i==n)
        {
            cout << "0\n";
            continue;
        }
        if (c!=0)
            v.emplace_back(c*2,1);
        c=0;
        int k = n-1;
        while (k>i && s[k]=='0') {k--; c++;}
        v.emplace_back(c*2,1);
        if (c!=0)
        c=0;
        k++;
        for (i++;i<k;i++)
        {
            if (s[i]=='0') c++;
            else
            {
                if (c!=0)
                    v.emplace_back(c,2);
                c=0;
            }
        }
        std::sort(v.begin(), v.end(), std::greater());
        int step = 0;
        int saved = 0;
        for (auto const& p : v)
        {
            //cout << step << ' ' << saved << ' ' << p.first << ' ' << p.second << endl;
            int a = p.first;
            if (p.second == 1)
            {
                a/=2;
                if (a<=step)
                    break;
                saved += a-step;
            }else
            {
                if (a<=2*step)
                    break;
                a-=step*2;
                if (a==1)
                    saved++;
                else
                {
                    saved += a-1;
                    step++;
                }
            }
            step++;
        }
        cout << n - saved << '\n';
    }
    
}