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#include <iostream>
#include <algorithm>
#include <vector>

using namespace std;

int main()
{
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);

    int z;
    cin >> z;
    while (z--)
    {
        int n;
        cin >> n;
        string S;
        cin >> S;

        vector<pair<int, bool>> V;
        char prev = 0;
        for (auto& s : S) {
            if (s == '0') {
                if (s == prev) V.back().first++;
                else V.push_back({ 1, false });
            }
            prev = s;
        }

        if (S.front() == '0') V.front() = { V.front().first * 2, true };
        if (S.back() == '0') V.back() = { V.back().first * 2, true };
        if (V.size() == 1 && S.front() == '0' && S.back() == '0') V.front().first /= 2;
        sort(V.rbegin(), V.rend());

        int res = 0, day = 0;
        for (auto [v, b] : V) {
            v -= 2 * day;
            if (b) v /= 2;
            if (v <= 0) continue;
            if (b || v == 1) res += v, day++;
            else if (v == 2) res += 1, day++;
            else res += v - 1, day += 2;
        }

        cout << n - res << '\n';
    }
}