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#include<bits/stdc++.h>
 
using namespace std;
 
using ll = long long;
using vi = vector<int>;
using pi = pair<int, int>;
using vpi = vector<pi>;
#define FOR(x, b, e) for(int x = b; x <= (e); ++x)
#define FORD(x, b, e) for(int x = b; x >= (e); --x)
#define REP(x, n) for(int x = 0; x < (n); ++x)
#define ALL(c) (c).begin(), (c).end()
#define ALLD(c) (c).rbegin(), (c).rend()
#define SIZE(x) ((int)(x).size())
#define pb push_back
#define pp emplace_back
#define st first
#define nd second
#define sq(a) (a)*(a)
const int inf = 1000000001;
const double eps = 1e-9;
bool fleq(double a, double b){
	return abs(a - b) < eps;
}

int t;
bool comp(pair<int,int>a, pair<int,int>b){
    return a.st*b.nd > b.st*a.nd;
}
int main(){
	ios_base::sync_with_stdio(0);
	cin.tie(0);
    cin >> t;
    while(t--){
        int n;
        ll ans = 0;
        int time = 0;
        bool b = false;
        string s;
        cin >> n >> s;
        vpi a;
        int j = 0;
        REP(i, n){
            if(s[i] == '0')j++;
            else {
                if(j > 0){
                    if(!b){
                        a.pp(j, 1);
                    }
                    else {
                        if(j <= 2) a.pp(1,1);
                        else a.pp(j, 2);
                        
                    }
                    j = 0;
                }
                b = true;
            }
        }
        if(j > 0){
            a.pp(j, 1);
        }
        sort(ALL(a), comp);
        for(auto i : a){
            //cout << i.st << ' ' << i.nd << ' ' << time << '\n';
            if(i.nd == 2){
                ll temp = i.st - 2 * time;
                if(temp == 1){
                    time++;
                    ans++;
                }
                else if(temp > 0){
                    time += 2;
                    ans += temp - 1;
                }
            }
            else{
                ll temp = i.st - time;
                if(temp > 0){
                    time++;
                    ans += temp;
                }
            } 
        }
        cout << n - ans << '\n';
    }
	return 0;
}