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#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
#ifdef LOCAL
#define debug(...) __VA_ARGS__
#else
#define debug(...) {}
#endif
void solve(){
    int i;
    int n;
    cin>>n;
    string s;
    cin>>s;
    vector<pair<int,bool> > pq;
    int akt = 0;
    for (i = 0; i < n; i++){
        if (s[i] == '0') akt++;
        else{
            if (!akt) continue;
            if (akt == i) pq.push_back({2*akt,1});
            else pq.push_back({akt,0});
            akt = 0;
        }
    }
    if (akt){
        if (akt == n){
            cout<<0<<"\n";
            return;
        }
        pq.push_back({2*akt,1});
    }
    stable_sort(pq.begin(),pq.end());
    int d = 0;
    int wy = 0;
    for (i = int(pq.size())-1; i > -1; i--){
        if (pq[i].second){
            //cout<<d<<" "<<pq[i].first/2<<"\n";
            if ((pq[i].first/2) < d) continue;
            wy += (pq[i].first/2)-d;
            d++;
        }else{
            //cout<<d<<" "<<pq[i].first<<"\n";
            if (pq[i].first < 2*d+1) continue;
            else if (pq[i].first < 2*d+3){
                wy++;
                d++;
            }else{
                wy += pq[i].first-2*d-1;
                d += 2;
            }
        }  
    }
    cout<<n-wy<<"\n";
}
int main(){
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);
    int t;
    cin>>t;
    while (t--) solve();
    return 0;
}