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#include <vector>
#include <iostream>
#include <sstream>
#include <math.h>
#include <sys/time.h>
#include <cstdlib>
#include <algorithm>
#include <cassert>
#include <cstring>
#include <fstream>
#include <set>
#include <map>
#include <iomanip>
#include <queue>

#define FOR(i,a,b)  for(__typeof(b) i=(a);i<(b);++i)
#define REP(i,a)    FOR(i,0,a)
#define FOREACH(x,c)   for(__typeof(c.begin()) x=c.begin();x != c.end(); x++)
#define ALL(c)      c.begin(),c.end()
#define CLEAR(c)    memset(c,0,sizeof(c))
#define SIZE(c) (int) ((c).size())

#define PB          push_back
#define MP          make_pair
#define X           first
#define Y           second

#define ULL         unsigned long long
#define LL          long long
#define LD          long double
#define II         pair<int, int>
#define DD         pair<double, double>
#define FF          pair<float,float>

#define VC	    vector
#define VI          VC<int>
#define VVI         VC<VI>
#define VVVI        VC<VVI>
#define VD          VC<double>
#define VS          VC<string>
#define VII         VC<II>
#define VDD         VC<DD>
#define VFF         VC<FF>
#define VVD         VC<VD>
#define VVVD        VC<VVD>
#define VULL         VC<ULL>

#define DB(a)       cerr << #a << ": " << a << endl;

using namespace std;

template<class T> void print(VC < T > v) {cerr << "[";if (SIZE(v) != 0) cerr << v[0]; FOR(i, 1, SIZE(v)) cerr << "," << v[i]; cerr << "]\n";}
template<class T> string i2s(T &x) { ostringstream o; o << x; return o.str(); }
VS split(string &s, char c = ' ') {VS all; int p = 0, np; while (np = s.find(c, p), np >= 0) {all.PB(s.substr(p, np - p)); p = np + 1;} if (p < SIZE(s)) all.PB(s.substr(p)); return all;}

void solve_test(){
    string s;
    cin >> s;
    int n = stoi(s);
    cin >> s;
    int j = 0;
    VII T;
    int start = 0;
    while (j < n){
        while (j < n && s[j] == '1') j++;
        if (j == n) break;
        start = j;
        while (j < n && s[j] == '0') j++;
        if (start == 0 || j == n)
            T.PB(MP(j-start,1));
        else
            T.PB(MP(j-start,2));
    }

    if (SIZE(T) == 0){ cout << n << endl; return;}
    if (T[0].X == n){ cout << 0 << endl; return;}

    REP(i,SIZE(T))
        if (T[i].Y == 1) 
            T[i].X = 2*T[i].X;

    sort(ALL(T));
    reverse(ALL(T));

    int rounds = 0;
    int score = 0;
    for(auto I : T){
        if (I.X <= 2*rounds)
            break;
        if (I.Y == 1){
            score += I.X/2-rounds;
            rounds += 1;
        } else{
            score += max(1,I.X-2*rounds-1);
            rounds += 2;
        }
    }
    cout << n-score << endl;
}

int main(int argc, char *argv[]){
    int T;
    cin >> T;
    REP(t,T)
        solve_test();
    return 0;
}