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#include <bits/stdc++.h>

using namespace std;
int n,i,a;
int sum;
char c;
bool d;
int poc;
int z;
int kon;
int t;
priority_queue <pair<int,bool> > q;
int main()
{
    std::ios_base::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);
    cin>>t;
    for(int g=0;g<t;g++)
    {
        sum=0;
        d=false;
        poc=0;
        z=0;
        while(!q.empty())q.pop();
        cin>>n;
        cin>>c;
        i=1;
        while(c=='0'&&i<n)
        {
            poc++;
            cin>>c;
            i++;
        }
        if(c=='0')poc++;
        while(i<n)
        {
            cin>>c;
            if(c=='0')z++;
            else if(z)
            {
                q.push({z,0});
                z=0;
            }
            i++;
        }
        kon=z;
        z=min(poc,kon);
        if(z)q.push({z*2,1});
        i=0;
        while(!q.empty())
        {
            a=q.top().first;
            a-=i;
            if(a>1)
            {
                if(q.top().second)
                {
                    d=true;
                    sum+=poc;
                    sum+=kon;
                    sum-=i;
                    sum--;
                    i+=4;
                }
                else
                {
                    sum+=a-1;
                    i+=4;
                }
            }
            else if(a==1)
            {
                if(q.top().second)
                {
                    d=true;
                    sum+=poc;
                    sum+=kon;
                    sum-=i;
                    sum--;
                    i+=4;
                }
                else
                {
                    sum++;
                    i+=2;
                }
            }
            else
            {
                break;
            }
            q.pop();
        }
        if(!d)
        {
            sum+=max(0,poc-(i/2));
            sum+=max(0,kon-(i/2));
        }
        cout<<n-sum<<endl;
    }
    return 0;
}