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// Arti1990, II UWr

#include <bits/stdc++.h>

#define forr(i, n)                  for(int i=0; i<n; i++)
#define FOREACH(iter, coll)         for(auto iter = coll.begin(); iter != coll.end(); ++iter)
#define FOREACHR(iter, coll)        for(auto iter = coll.rbegin(); iter != coll.rend(); ++iter)
#define lbound(P,K,FUN)             ({auto SSS=P, PPP = P-1, KKK=(K)+1; while(PPP+1!=KKK) {SSS = (PPP+(KKK-PPP)/2); if(FUN(SSS)) KKK = SSS; else PPP = SSS;} PPP;})
#define testy()                     int _tests; scanf("%d", &_tests); FOR(_test, 1, _tests)
#define CLEAR(tab)                  memset(tab, 0, sizeof(tab))
#define CONTAIN(el, coll)           (coll.find(el) != coll.end())
#define FOR(i, a, b)                for(int i=a; i<=b; i++)
#define FORD(i, a, b)               for(int i=a; i>=b; i--)
#define MP                          make_pair
#define PB                          push_back
#define ff                          first
#define ss                          second
#define deb(X)                      X;

#define M 1000000007
#define INF 1000000007LL

using namespace std;

int n, m, a;
char slowo[1000007];

bool comp(pair<int, int> a, pair<int, int> b)
{
    return (a.ff)*b.ss > (b.ff)*a.ss;
}

int solve()
{
    scanf("%d %s", &n, &slowo);
    int ile = 0;
    vector <pair<int, int>> v;
    forr(i, n)
        if(slowo[i] == '0')
            ile++;
        else
        {
            if(ile > 0)
                v.PB(MP(ile, ile == i ? 1 : 2));
            ile = 0;
        }

    if(ile == n)
    {
        printf("%d\n", 0);
        return 0;
    }

    if(ile > 0)
        v.PB(MP(ile, 1));

    sort(v.begin(), v.end(), comp);
    long long res = 0;

    ile = 0;
    for(auto el : v)
    {
//        cout << el.ff << " " << el.ss << endl;
        if(el.ss == 1)
        {
            res += max(0, el.ff-ile);
            ile++;
        }
        else // el.ss == 2
        {
            res += max(el.ff > 2*ile ? 1 : 0, el.ff-ile-ile-1);
            ile += 2;
        }
    }

    printf("%lld\n", n-res);

    return 0;
}

int main()
{
    testy()
        solve();

    return 0;
}