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#include <cstdio>
#include <queue>

void przypadek()
{
    int n;
    scanf("%d\n", &n);
    
    std::priority_queue<int> one;
    std::priority_queue<int> two;
    
    int i = 0;
    int c = 0;
    char x;
    
    for (; i < n; i++)
    {
        scanf("%c", &x);
        if (x == '0')
            c++;
        else
        {
            if (c > 0)
                one.push(c);
            c = 0;
            for (i++; i < n; i++)
            {
                scanf("%c", &x);
                if (x == '0')
                {
                    c++;
                    break;
                }
            }
            break;
        }
    }
    
    for (i++; i < n; i++)
    {
        scanf("%c", &x);
        if (x == '0')
            c++;
        else
        {
            two.push(c);
            c = 0;
            for (i++; i < n; i++)
            {
                scanf("%c", &x);
                if (x == '0')
                {
                    c++;
                    break;
                }
            }
        }
    }
    
    if (c > 0)
        one.push(c);
    
    int p, q;
    int uratowane = 0;
    
    for (i = 0; !one.empty() || !two.empty(); i++)
    {
        if (!one.empty())
        {
            p = one.top() - i;
            if (p < 1)
                one = {};
        }
        else
            p = 0;
        
        if (!two.empty())
        {
            q = two.top() - 2*i;
            if (q < 1)
                two = {};
        }
        else
            q = 0;
        
        if (p+1 >= q && p > 0)
        {
            uratowane += p;
            one.pop();
        }
        
        if (q > p+1 && q > 0 || (p == 0 && q == 1))
        {
            uratowane += 1;
            one.push(q + i - 1);
            two.pop();
        }
    }
    
    printf("%d\n", n - uratowane);
}

int main()
{
    int t;
    scanf("%d\n", &t);
    for (int i = 0; i < t; i++)
        przypadek();
    return 0;
}