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#include <iostream>
#include <algorithm>
#define ll long long
using namespace std;

ll t, n, i;
pair<ll, bool> groups[100000];//..., is border
char c;
bool b[100000];
ll gr;
ll x, y;
ll r;

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

    cin >> t;
    for (int o = 0; o < t; ++o) {
        cin >> n;
        i = 0;
        gr = 0;
        x = 0;
        y = 0;
        r = 0;

        for (int j = 0; j < n;  ++j) {
            cin >> c;
            b[j] = c == '1';
        }

        for (; i < n; ++i) {
            if (b[i]) break;
            x++;
        }

        if (i == n) {
            cout << 0 << endl;
            continue;
        }

        groups[0] = { 2 * x, 1 };
        gr = 1;
        x = 0;

        if (i == 0) i = 1;

        for (; i < n; ++i) {
            if (b[i]) {
                if (x > 0) {
                    groups[gr] = { x, 0 };
                    gr++;
                    x = 0;
                }
            }
            else x++;
        }

        groups[gr] = { 2 * x, 1 };
        gr++;

        sort(groups, groups + gr, greater<pair<ll, bool>>());

        for (int j = 0; j < gr; ++j) {
            groups[j].first -= 2*y;
            if (groups[j].first <= 0) break;

            if (groups[j].second) {
                y++;
                r += groups[j].first / 2;
            }
            else {
                y += 2;
                r += max(groups[j].first - 1, (ll)1);
            }
        }

        cout << n - r << endl;
    }
}