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#include <bits/stdc++.h>
using namespace std;
using LL = long long;
#define FOR(i, l, r) for(int i = (l); i <= (r); ++i)
#define REP(i, n) FOR(i, 0, (n) - 1)
#define ssize(x) int(x.size())
template<class A, class B> auto& operator<<(ostream &o, pair<A, B> p) {
    return o << '(' << p.first << ", " << p.second << ')';
}
template<class T> auto operator<<(ostream &o, T x) -> decltype(x.end(), o) {
    o << '{'; int i = 0; for(auto e : x) o << (", ")+2*!i++ << e; return o << '}';
}
ostream& operator<<(ostream &o, string &s) {
    return o << s.data();   
}
#ifdef DEBUG
#define debug(x...) cerr << "[" #x "]: ", [](auto... $) {((cerr << $ << "; "), ...); }(x), cerr << '\n'
#else
#define debug(...) {}
#endif

int main() {
    cin.tie(0)->sync_with_stdio(0);

    int q;
    cin >> q;
    while (q--) {
        int n;
        string s;
        cin >> n >> s;
        vector<vector<int> > cnt(2 * n + 3, vector<int>(2));

        bool fst = false;
        int now = 0;
        REP(i, n) {
            if (s[i] == '0')
                now++;
            else {
                if (now == 0) {
                    fst = true;
                    continue;
                }
                if (!fst) {
                    fst = true;
                    cnt[2 * now][0]++;
                }
                else {
                    if (now <= 1)
                        cnt[1][0]++;
                    else
                        cnt[now - 1][1]++;
                }
                now = 0;
            }
        }
        if (now != 0)
            cnt[2 * now][0]++;

        int tms = 0;
        int x, ans = 0;
        for (int i = 2 * n + 2; i > 0 && i - tms * 2 >= 0; i--) {
            if (cnt[i][1] > 0) {
                cnt[i][1]--;
                x = i - tms * 2;
                if (x == 0)
                    x = 1;
                ans += x;
                if (x == 1)
                    tms++;
                else
                    tms += 2;
                i++;
            }
            else if (cnt[i][0] > 0) {
                cnt[i][0]--;
                x = i - tms * 2;
                if (x > 0) {
                    ans += (x + 1) / 2;
                    tms++;
                }
                i++;
            }
        }
        cout << n - ans << '\n';
    }

    return 0;
}