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#include <bits/stdc++.h>
using namespace std;
 
#define ll long long
#define p_b push_back
#define m_p make_pair
#define fi first
#define se second
 
ll inf = 8000000000000000000;
ll mod = 30000;
const int maxn = 200003;

bool cmp(int a, int b){
    return abs(a)>abs(b);
}
int main(){
    ios_base::sync_with_stdio(0);
    int z; cin>>z;
    while(z--){
        int n; cin>>n;
        string s; cin>>s;
        vector<int> t1;
        int ost = -1;
        for(int i = 0; i<n; i++)
            if(s[i]=='1'){
                if(ost==-1) 
                    t1.p_b(-(i-ost-1)*2);
                else
                    t1.p_b(i-ost-1);

                ost = i;
            }

        t1.p_b(-(n-ost-1)*2);
        sort(t1.begin(), t1.end(), cmp);
        int res = 0, ti = 0;
        for(int i = 0; i<(int)t1.size(); i++){
            //cout<<t1[i]<<" "<<res<<" "<<ti<<endl;
            if(t1[i]<0){
                int d = -t1[i]/2-ti;
                if(d<=0) continue;
                res += max(0, d);
                ti++;
            } 
            else{
                int d = t1[i]-ti*2;
                if(d<=0) continue;
                if(d<=1) res += max(0, d);
                else res += max(0, d-1);
                if(d<=2) ti++;
                else ti += 2;
            }
        }

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