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#include <bits/stdc++.h>
using namespace std;
int w,n,k,b,poc,kon,s,it,p,ile,tab[100001];
string a;
bool c1,c2;
int main()
{
ios_base::sync_with_stdio(false);
cin.tie(NULL);
cout.tie(NULL);
cin>>n;
for(int i=0;i<n;++i)
	{
	cin>>k;
	cin>>a;
	poc=0;kon=k-1;w=0;ile=0;p=0;it=0;
	c1=true;c2=true;
	for(int i=0;i<k;++i){if(a[i]=='0')ile++;}
	while(c1&&poc<k)
		{
		if(a[poc]=='0')
			{
			poc++;
			}
		else{c1=false;}
		}
	while(c2&&kon>0)
		{
		if(a[kon]=='0')
			{
			kon--;
			}
		else{c2=false;}
		}
	kon++;
	//cout<<poc<<" "<<kon;
	for(int i=poc+1;i<kon;++i)
		{
		if(a[i]=='0')
			{
			s++;
			}
		else if(a[i]=='1')
			{
			tab[it]=s;
			it++;
			s=0;
			}
		}
	//it--;
	sort(tab,tab+it);kon=k-kon;
	//for(int i=0;i<it;++i){cout<<tab[i]<<" ";}cout<<"\n";
		//cout<<it<<" "<<poc<<" "<<kon<<"\n";
	it--;
	if(ile==k){cout<<0<<"\n";}
	else
		{
		while(tab[it]-2*p>0)
			{
		//	cout<<tab[it]-2*p-1<<" "<<kon-p<<" "<<poc-p<<"\n";
			if(poc-p>=tab[it]-2*p-1)
				{
				w+=(poc-p);
				poc=0;
				p++;
				}
			else if(tab[it]-2*p-1<2)
				{
				p++;
				it--;
				w++;
				}
			else if(kon-p>=tab[it]-2*p-1)
				{
				w+=(kon-p);
				kon=0;
				p++;
				}
			
			else 
				{
				w+=tab[it]-2*p-1;
				it--;
				p+=2;
				}
			}
		if(kon-p>0){w+=kon-p;p++;}
		if(poc-p>0){w+=poc-p;p++;}
		//cout<<w;
		cout<<k-w<<"\n";
		}
	for(int i=0;i<k;++i){tab[i]=0;}
	}
}