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#include<bits/stdc++.h>
#define ll long long
#define pii pair<int, int>
#define st first
#define nd second
#define turbo ios_base::sync_with_stdio(false);cin.tie(0);cout.tie(0);
#define pb push_back
#define vi vector<int>
#define vvi vector<vi>
#define qi queue<int>
#define ld long double

using namespace std;

/*---------------------------------------------------------///CODE///---------------------------------------------------------*/

void solve()
{
    int n; cin >> n;
    string s; cin >> s;

    priority_queue<pair<pii, pii> > q;

    int x = -1, y = -1;

    for(int i = 0; i < s.size(); i++)
        if(s[i] == '1' && x == -1)
            x = i, y = i;
        else if(s[i] == '1')
            y = i;

    if(x == -1)
    {
        cout << 0 << "\n";
        return;
    }

    for(int i = 0; i < s.size(); i++)
        if(s[i] == '0')
        {
            int j = i + 1;

            while(j < s.size() && s[j] == '0')
                j ++;
            if(i > x && i < y) q.push({{(j - i + 1) >> 1, -2}, {j - i, 0}});
            else q.push({{j - i, -1}, {j - i, 0}});
            i = j - 1;
        }

    int curr = 0;
    int res = n;

    while(!q.empty())
    {
        auto f = q.top();
        q.pop();

        int ile_zostalo = max(0, f.nd.st - (curr - f.nd.nd) * (-f.st.nd));

        if(f.st.nd == -1)
        {
            res -= ile_zostalo;
            curr ++;
            continue;
        }

        if(ile_zostalo > 0)
        {
            res -= 1;
            if(ile_zostalo > 1) q.push({{ile_zostalo + curr - 1, -1}, {ile_zostalo - 1, curr}});
        }
        curr ++;
    }
    cout << res << "\n";
}
int main()
{
    turbo

    int t; cin >> t;

    while(t--)
        solve();

    return 0;
}