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#define _CRT_SECURE_NO_WARNINGS 1
#define _WINSOCK_DEPRECATED_NO_WARNINGS 1

#include <iostream>
#include <string>
#include <vector>
#include <algorithm>

using namespace std;


struct Ciag
{
    int value;
    int multi;
};
using namespace std;

int main()
{
    int t, n;
    scanf("%d", &t);



    for (int i = 0; i < t; ++i)
    {
        scanf("%d", &n);
        string str;
        getline(std::cin, str);

        int zarazone = 0;
        char lastOne = 'n';
        int lastLength = 0;
        bool pierwszy = true;
        vector<int> jedynki;
        vector<int> dwojki;

        for (int j = 0; j < n; ++j)
        {
            char p;
            scanf("%c", &p, 1);

            if (p == '1')
            {
                zarazone++;

                if (lastOne == '0')
                {
                    if (pierwszy)
                    {
                        jedynki.push_back(lastLength);
                        
                    }
                    else
                    {
                        dwojki.push_back(lastLength);
                    }
                }
                pierwszy = false;
                lastOne = '1';
                lastLength = 0;
            }
            else
            {
                lastOne = '0';
                lastLength++;
            }
        }
        if (lastLength > 0)
        {
            jedynki.push_back(lastLength);
            lastLength = 0;
        }

        if (zarazone == 0)
        {
            printf("0\n");
            continue;
        }

        sort(jedynki.begin(), jedynki.end());
        sort(dwojki.begin(), dwojki.end());

        int time = 0;
        int uratowani = 0;
        while (true)
        {
            int jv = -1;
            int dv = -1;
            if (!jedynki.empty())
            {
                jv = jedynki.back();
            }
            if (!dwojki.empty())
            {
                dv = dwojki.back();
            }

            if (jv == -1 && dv == -1)
            {
                break;
            }

            int tjv = jv - time;
            int tdv = dv - 2 * time;

            if (tjv <= 0 && tdv <= 0)
            {
                break;
            }


            if ((tjv < tdv-2) || (tjv <= 0 && tdv >0))
            {
                dwojki.pop_back();
                if (tdv == 1)
                {
                    uratowani += max(tdv, 0);
                    time++;
                }
                else
                {
                    uratowani += max(tdv - 1, 0);
                    time++; time++;
                }
            }
            else
            {
                jedynki.pop_back();
                uratowani += tjv;
                time++;
            }
        }

        int wynik = n - uratowani;
        printf("%d\n", wynik);
    }
}