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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 << '}';
}
#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 t;
    cin >> t;

    REP(_t, t) {
        int n;
        cin >> n;
        string state;
        cin >> state;

        vector<pair<int, int>> len = {{0, 0}};
        REP(i, n) {
            if(state[i] == '0')
                len.back().first++;
            else
                len.emplace_back(0, i + 1);
        }

        len[0].first *= 2;
        len.back().first *= 2;

        sort(len.rbegin(), len.rend());

        int turns = 0, ans = 0;
        for(auto &[x, l] : len) {
            if(x == 0) continue;

            assert(state[l] == '0');
            int r = l;
            while(r + 1 < n && state[r + 1] == '0')
                r++;

            if(l != 0) l += turns;
            if(r != n - 1) r -= turns;

            int is_side = l == 0 || r == n - 1;
            int to_add = r - l + 1;
            if(!is_side && to_add > 1) to_add--;
            if(to_add < 0) continue;
            ans += to_add;
            turns += 2 - is_side;
        }

        cout << n - ans << "\n";
    }
}