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#include <iostream>
#include <vector>
#include <algorithm>
using namespace std;

struct interv{
    int length;
    bool special;
};

int t, n;
char c;
vector<interv> intervals;

bool compare(interv a, interv b) {
    if(a.special == b.special) {
        return a.length > b.length;
    } else if(!a.special && b.special) {
        return a.length > b.length*2;
    } else { // if(a.special && !b.special)
        return a.length*2 > b.length;
    }
}

int main() {
    cin >> t;
    while(t --> 0) {
        vector<interv>().swap(intervals);
        cin >> n;
        int length = 0;
        for(int i=0; i<n; i++) {
            cin >> c;
            if(c == '0') length++;
            else {
                if(length != 0) {
                    intervals.push_back({length, length == i});
                    length = 0;
                }
            }
        }
        if(length > 0) intervals.push_back({length,true});
        sort(intervals.begin(), intervals.end(), compare);
        int days_spent = 0;
        int survived = 0;
        for(int i=0; i<intervals.size(); i++) {
            if(intervals[i].special) {
                if(days_spent >= intervals[i].length) break;
                survived += intervals[i].length-days_spent;
                days_spent++;
            } else {
                length = intervals[i].length-days_spent*2;
                if(length <= 0) break;
                if(length <= 2) {
                    survived++;
                    days_spent++;
                } else {
                    survived += length-1;
                    days_spent += 2;
                }
            }
        }
        cout << n-survived << endl;
    }
}