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

int main()
{
    ios_base::sync_with_stdio(0);
    cout.tie(0);
    cin.tie(0);
    int t; cin >> t;
    while (t--)
    {
        int n; cin >> n;
        string s; cin >> s;
        vector<pair<int, int>> v;
        int l = 0;
        for (int i = 0; i < n; i++)
        {
            if (s[i] == '0') l++;
            else 
            {
                v.push_back({l, 0});
                l = 0;
            }
        }
        v.push_back({l, 0});
        if (v.size() == 1) 
        {
            cout << 0 << '\n';
            continue;
        }
        v[0].first *= 2;
        v[0].second = 1;
        v.back().first *= 2;
        v.back().second = 1;   
        sort(v.begin(), v.end(), [](pair<int, int>a, pair<int, int> b)
        {
            if (a.first != b.first) return a.first > b.first;
            return a.second > b.second;
        });
        int r = 0, ans = 0;
        for (int i = 0; i < v.size(); i++)
        {
            if (v[i].second == 1)
            {
                ans += max(0, v[i].first/2-r);
                r++;
            }
            else if (v[i].first > 2*r)
            {
                ans += 1;
                v[i].first -= 2*r+2;
                ans += max(v[i].first, 0);
                r += 2;
            }
        }
        cout << n-ans << '\n';
    }
    
}