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#include <bits/stdc++.h>

using namespace std;

typedef unsigned uint;
typedef long long ll;
typedef unsigned long long ull;
typedef long double ldbl;
typedef pair<int, int> pii;
typedef pair<uint, uint> puu;
typedef pair<ll, ll> pll;
typedef pair<ull, ull> pull;
typedef pair<double, double> pdd;
typedef vector<int> vi;
typedef vector<uint> vu;
typedef vector<ll> vll;
typedef vector<ull> vull;
typedef vector<pii> vpii;
typedef vector<puu> vpuu;
typedef vector<pll> vpll;
typedef vector<pull> vpull;
typedef vector<string> vstr;
typedef vector<double> vdbl;
typedef vector<ldbl> vldbl;
#define pb push_back
#define ppb pop_back
#define pfr push_front
#define ppfr pop_front
#define emp emplace
#define empb emplace_back
#define be begin
#define rbe rbegin
#define all(x) (x).be(), (x).end()
#define rall(x) (x).rbe(), (x).rend()
#define fir first
#define sec second
#define mkp make_pair
#define brif(cond) if (cond) break
#define ctif(cond) if (cond) continue
#define retif(cond) if (cond) return
void canhazfast() {ios_base::sync_with_stdio(false);cin.tie(nullptr);cout.tie(nullptr);}
template<typename T> T gcd(T a, T b) {return b ? gcd(b, a%b) : a;}
template<typename T> T extgcd(T a, T b, T &x, T &y)
{
    T x0 = 1, y0 = 0, x1 = 0, y1 = 1;
    while (b) {
        T q = a/b; a %= b; swap(a, b);
        x0 -= q*x1; swap(x0, x1);
        y0 -= q*y1; swap(y0, y1);
    }
    x = x0; y = y0; return a;
}
int ctz(uint x) {return __builtin_ctz(x);}
int ctzll(ull x) {return __builtin_ctzll(x);}
int clz(uint x) {return __builtin_clz(x);}
int clzll(ull x) {return __builtin_clzll(x);}
int popcnt(uint x) {return __builtin_popcount(x);}
int popcntll(ull x) {return __builtin_popcountll(x);}
int bsr(uint x) {return 31^clz(x);}
int bsrll(ull x) {return 63^clzll(x);}

#define N 100032

char s[N];

void solve()
{
    int n, t = 0, f0 = 0, cnt = 0, ans = 0;
    bool pref = true;
    vi v1, v2;

    cin >> n >> s;
    for (int i = 0; i < n; ++i) {
        if (s[i] == '0') {
            ++cnt;
        } else {
            if (cnt) {
                f0 += cnt;
                if (pref) v1.pb(cnt);
                else v2.pb(cnt);
            }
            pref = false;
            cnt = 0;
        }
    }
    if (cnt) {
        f0 += cnt;
        v1.pb(cnt);
    }
    sort(all(v1));
    sort(all(v2));
    //cerr << "p/s:"; for (int x : v1) cerr << ' ' << x; cerr << '\n';
    //cerr << "mid:"; for (int x : v2) cerr << ' ' << x; cerr << '\n';
    retif(f0 == n) cout << "0\n", void();
    while (v1.size() && v2.size()) {
        int sz1 = v1.back(), sz2 = v2.back();
        if (sz2 >= 2*sz1) {
            /// use 2
            v2.ppb();
            sz2 = max(sz2-2*t, 0);
            if (sz2 > 0) {
                ++ans;
                --sz2;
            }
            ++t;
            ans += max(sz2-1, 0);
            ++t;
        } else {
            /// use 1
            v1.ppb();
            ans += max(sz1-t, 0);
            ++t;
        }
    }
    while (v1.size()) {
        int sz1 = v1.back();
        v1.ppb();
        ans += max(sz1-t, 0);
        ++t;
    }
    while (v2.size()) {
        int sz2 = v2.back();
        v2.ppb();
        sz2 = max(sz2-2*t, 0);
        if (sz2 > 0) {
            ++ans;
            --sz2;
        }
        ++t;
        ans += max(sz2-1, 0);
        ++t;
    }
    ans = n-ans;
    cout << ans << '\n';
}

int main()
{
    canhazfast();

    int t;
    cin >> t;
    for (; t; --t) solve();

    return 0;
}