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

struct Interval {
    long long  opened, length;
    Interval(long long  opened, long long  length) {
        this->opened = opened;
        this->length = length;
    }
};

struct ord {
    inline bool operator() (const Interval& in1, const Interval& in2) {
        return (2 - in2.opened) * in2.length < (2 - in1.opened) * in1.length;
    }
};

int main() {
    ios_base::sync_with_stdio(0);
    cin.tie(0);

    long long  t;
    cin >> t;
    for (; t > 0; t--) {
        long long n, range = 0, left = 1;
        string str;
        cin >> n >> str; str.append("#");
        vector<Interval> v;
        for (int i = 0; i <= n; i++) {
            if (str[i] == '0') {
                range += 1;
            }
            else {
                if (range > 0) {
                    if (left || str[i] == '#') {
                        Interval in(0, range);
                        v.push_back(in);
                    }
                    else {
                        Interval in(1, range);
                        v.push_back(in);
                    }
                }
                range = 0;
                left = 0;
            }
        }
        
        long long acc = 0, steps = 0;
        sort(v.begin(), v.end(), ord());
        for (int i = 0; i < v.size(); i++) {
            if (v[i].opened == 0) {
                if (v[i].length - steps > 0) {
                    acc += v[i].length - steps;
                }
                steps += 1;
            }
            else {
                if (v[i].length - 2 * steps > 0) {
                    long long add = v[i].length - 2 * steps - 1;
                    if (add < 1) {
                        add = 1;
                    }
                    acc += add;
                }
                steps += 2;
            }
        }

        long long res = n - acc;
        cout << res << endl;
    }


    return 0;
}