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#include <iostream>
#include <string>
#include <algorithm>
//#include <bits/stdc++.h>
using namespace std;
int tab[100009] {};
int main()
{
ios_base::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);

string s;
int t,n,l=-100,p=-100,x=0,mia=0,ix=0,dz=0,k=0,ile=0,mmax=0,nx=0,dx=0;

cin>>t;

for (int i=0;i<t;i++)
{
cin>>n>>s;
l=-100,p=-100,x=0,mia=0,ix=0,dz=0,k=0,ile=0,mmax=0,nx=0,dx=0;

while (x<n)
{
mia=0;
if ((s[x]=='0'))
{
mia=0;
while ((s[x]=='0') && x<n)
{
mia++;
x++;}
x--;
tab[ix]=mia;
ix++;
mia=0;
}
x++;
}

tab[ix]=-100,tab[ix+1]=-100;

if (ix==0)
{cout<<n<<"\n";
continue;}

if (ix==1 && tab[0]==n)
{cout<<"0\n";
continue;}

if (s[n-1]=='0')
{p=tab[ix-1];
tab[ix-1]=-100;}

if (s[0]=='0')
{l=tab[0];
tab[0]=-100;}

if (p>l) {swap(p,l);}

sort (tab,tab+ix);
reverse (tab,tab+ix);

ix=0,dz=0,ile=0;

while (1)
{
nx=2;
mmax=tab[ix]-(2*dz)-1;
dx=1;

if ((tab[ix]-(2*dz)==1) || (tab[ix]-(2*dz)==2))
{mmax=1;
nx=1;}

if (l-dz>0)
{
if (l-dz>(mmax+1)/2)
{mmax=l-dz;
l=-1000;
dx=0;
nx=1;}
}
else if (p-dz>0)
{
if (p-dz>(mmax+1)/2)
{mmax=p-dz;
p=-1000;
dx=0;
nx=1;}
}

dz=dz+nx;
ix=ix+dx;
if (mmax<1) {break;}
ile=ile+mmax;
}

cout<<n-ile<<"\n";
}

return 0;
}