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

using namespace std;

string cities;
vector<pair<int, int>> seqs;
int t, n;

int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);

    cin >> t;
    while (t--) {
        seqs.clear();
        cin >> n;
        cin >> cities;
        int currentSeq = 0;
        for (int i = 0; i < n; ++i) {
            if (cities[i] == '0') {
                ++currentSeq;
            } else {
                if (currentSeq > 0) {
                    if (i != currentSeq) {
                        seqs.push_back(make_pair(currentSeq, 2));
                    } else {
                        seqs.push_back(make_pair(2*currentSeq, 1));
                    }
                }
                currentSeq = 0;
            }
        }
        if (currentSeq == n) {
            cout << 0 << endl;
            continue;
        } else if (currentSeq > 0) {
            seqs.push_back(make_pair(2*currentSeq, 1));
        }
        sort(seqs.begin(), seqs.end());
        int result = 0, cnt = 0;
        for (auto rit = seqs.rbegin(); rit != seqs.rend(); ++rit) {
            if (rit->first - 2*cnt <= 0) {
                break;
            }
            if (rit->second == 1) {
                result += (rit->first/2 - cnt);
            } else {
                result++;
                if (rit->first - 2*cnt > 1) {
                    result += rit->first - 2 - 2*cnt;
                    cnt++;
                }
            }
            cnt++;
        }
        cout << n - result << endl;
    }

    return 0;
}