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#include<bits/stdc++.h>
using namespace std;
#define d(a)cout<<#a<<" = "<<a<<"\n";
//#define f first
//#define s second
#define mp make_pair
#define TURBO ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
#define ll long long
vector<int>health;

int main(){
    TURBO;
    int t;
    cin>>t;
    while (t--) {
        health.clear();
        int n;
        string s;
        cin>>n;
        cin>>s;
        int first=-1,last=-1,cur=0;
        
        for(int i=0;i<n;i++){
            
            bool x=(s[i]=='1');
            if(x){
                if(first==-1)first=cur;
                else if(cur)health.push_back(cur);
                cur=0;
            }
            else cur++;
            if(i+1==n)last=cur;
            //d(cur);
           
        }
        health.push_back(0);
        sort(health.begin(),health.end(),greater<int>());
        int wyleczone=0;
        int zatrute=0;
        //bool f=1,l=1;
        //d((health[0]==1 and first<1 and last<1))
        if(health.size())if(health[0]==1 and first<1 and last<1)wyleczone++;
        //d(last);d(first);for(auto i:health)d(i);
        for(int i=0;i<health.size();){
            //d(health[i]);
            int h=max(max(first-zatrute,last-zatrute),health[i]-zatrute-zatrute-1);
            //d(h)
            if(h>0) wyleczone+=h;
            else break;
            
            if(h==first){
                zatrute++;
                first=0;
            }
            else if(h==last){
                zatrute++;
                last=0;
            }
            else{
                i++;
                zatrute+=2;
            }
        }
        cout<<n-wyleczone<<"\n";
    }
}

/*
3
8
00110100
10
1001000010
4
0000
 
 */