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#include <cstdio>
#include <list>
#include <math.h>


using namespace std;

struct CitySequence {
    int infected;
    int length;
    int from_left;
    int from_right;
    bool processed;

    CitySequence(int length, int infected) {
        this->length = length;
        this->infected = infected;
        this->from_left = 1;
        this->from_right = 1;
        this->processed = false;
    }

    void print(int day) {
        printf(
            "day: %d, processed: %d, infected: %d, length: %d, from_left: %d, from_right: %d, cities: %d, saves: %d\n",
            day,
            this->processed ? 1 : 0,
            this->infected,
            this->length,
            this->from_left,
            this->from_right,
            this->get_cities_left(day),
            this->get_possible_saves(day)
        );
    }

    int get_cities_left(int day) const {
        return max(this->length - (this->from_left + this->from_right) * day, 0);
    }

    int get_possible_saves(int day) const {
        int cities_left = this->get_cities_left(day);

        if (cities_left) {
            if (this->from_left + this->from_right == 2 && cities_left < 3) {
                return 0;
            }

            return cities_left - (this->from_left + this->from_right) - ((this->from_left + this->from_right)/2);
        }

        return 0;
    }

    ~CitySequence() {}
};

int get_sequence_length(char A[], int start, int end) {
    char c = A[start];
    int result = 0;

    while(start + result < end && A[start + result] == c) result++;

    return result;
}

int get_solution(list<CitySequence>& city_sequences, int n) {
    int cities_saved = 0;
    int day = 0;
    CitySequence* first_sequence = &city_sequences.front();
    CitySequence* last_sequence = &city_sequences.back();
    list<CitySequence>::iterator it;

    city_sequences.sort([](const CitySequence& a, const CitySequence& b) {
        int a_saves = a.get_possible_saves(0);
        int b_saves = b.get_possible_saves(0);

        return a_saves > b_saves;
    });

    for (it = city_sequences.begin(); it != city_sequences.end();) {
        CitySequence* sequence_to_process = &(*it);
        int first_possible_saves = first_sequence->get_possible_saves(day);
        int last_possible_saves = last_sequence->get_possible_saves(day);
        int vaccines = 0;
        bool swapped = false;
        bool weird = false;

        if (!first_sequence->processed && first_possible_saves >= sequence_to_process->get_possible_saves(day)) {
            sequence_to_process = first_sequence;
            swapped = true;
        }

        if (!last_sequence->processed && last_possible_saves >= sequence_to_process->get_possible_saves(day)) {
            sequence_to_process = last_sequence;
            swapped = true;
        }

        int possible_saves = sequence_to_process->get_possible_saves(day);
        int cities_left = sequence_to_process->get_cities_left(day);

        if (!sequence_to_process->processed && possible_saves) {
        // sequence_to_process->print(day);
            cities_saved += possible_saves;
            vaccines = cities_left > 2 ? sequence_to_process->from_left + sequence_to_process->from_right : min(1, sequence_to_process->from_left + sequence_to_process->from_right);
            cities_saved += vaccines;
            day += vaccines;
            sequence_to_process->processed = true;

            if (swapped) weird = true;
        }
        if (!weird) {
            ++it;
        }
    }

    for (auto &city_sequence : city_sequences) {
        int cities_left = city_sequence.get_cities_left(day);
        int vaccines = 0;

        if (!city_sequence.processed && cities_left) {
            // city_sequence.print(day);
            vaccines = cities_left > 2 ? city_sequence.from_left + city_sequence.from_right : min(1, city_sequence.from_left + city_sequence.from_right);

            cities_saved += vaccines;
            day += vaccines;
        }
    }

    return n - cities_saved;
}

int main(int argc, char const *argv[]) {
    int t;
    scanf("%d", &t);

    for (size_t i = 0; i < t; i++) {
        int n;
        list<CitySequence> city_sequences;
        char* cities;
        scanf("%d", &n);
        // printf("%d\n", n);

        cities = new char[n + 100];
        scanf("%s", cities);

        for (int j = 0; j < n;) {
            char infected = cities[j] - '0';
            int length = get_sequence_length(cities, j, n);
            CitySequence new_sequence = CitySequence(length, infected);

            city_sequences.push_back(new_sequence);

            j += length;
        }

        city_sequences.front().from_left = 0;  
        city_sequences.back().from_right = 0;
        city_sequences.remove_if(
            [](const CitySequence& city) {
                return city.infected;
            }
        );

        // for (auto &&city_sequece : city_sequences) {
        //     city_sequece.print(0);
        // }
        
        printf("%d\n", get_solution(city_sequences, n));

        delete[] cities;
    }

    return 0;
}