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// Problem: Pandemia [B]
// https://sio2.mimuw.edu.pl/c/pa-2021-1/p/pan/

#include <cstdio>
#include <cmath>
#include <iostream>
#include <algorithm>
#include <string>
#include <cctype>
#include <vector>
#include <set>
#include <map>
using namespace std;
#define REP(i,n) for(int _n=(n), i=0;i<_n;++i)
#define FOR(i,a,b) for(int i=(a),_b=(b);i<=_b;++i)
#define FORD(i,a,b) for(int i=(a),_b=(b);i>=_b;--i)
#define FOREACH(e, v) for(auto const &e: v)
#define IN(e, s) (s).find((e)) != (s).end()
#define TRACE(x) cerr << "TRACE(" #x ")" << endl;
#define DEBUG(x) cerr << #x << " = " << (x) << endl;
#define PB push_back
#define ST first
#define ND second
#define ALL(c) (c).begin(), (c).end()
#define SZ(x) ((int)(x).size())
typedef long long LL; typedef unsigned long long ULL; typedef unsigned short UST; typedef unsigned int UINT;
typedef vector<int> VI;
inline  void fix_io() { cin.tie(nullptr); ios::sync_with_stdio(false); }

bool is_safe(int start, int end, vector<int>& v) {
    if (start == 0) {
        if (end == v.size()-1) {
            return true;
        } else {
            if (v[end+1] == -1) {
                return true;
            }
        }
    } else {
        if (end == v.size()-1) {
            if (v[start-1] == -1) return true;
        } else {
            if (v[start-1] == -1 && v[end+1] == -1) return true;
        }
    }
    return false;
}

int infect(vector<int>& v) {
    int infected = 0;
    FOR(i,0,v.size()-1) {
        if (v[i]==1) {
            if (i != 0) {
                if (v[i-1] == 0) {
                    v[i-1] = 2;
                    infected++;
                }
            }
            if (i != v.size()-1) {
                if (v[i+1] == 0) {
                    v[i+1] = 2;
                    infected++;
                }
            }
        }
    }
    // How can we achive it without additional loop?
    FOR(i,0,v.size()-1) 
        if (v[i]==2)
            v[i] = 1;
    return infected;
}

int count_infected(vector<int>& v) {
    int count = 0;
    FOR(i,0,v.size()-1)
        if (v[i] == 1)
            count++;
    return count;
}

int vaccination_index(vector<int>& v) {
    bool in = false;
    int max_size = -1;
    int tstart = -1;
    int tend = -1;
    int start_max = -1;
    int end_max = -1;
    FOR(i,0,v.size()-1) {
        if (in) {
            if (v[i] == 0) {
                if (i == v.size() - 1) { // last element
                    tend = i;
                    int size = tend-tstart+1;
                    if (!is_safe(tstart, tend, v))
                        if (size > max_size) {
                            max_size = size;
                            start_max = tstart;
                            end_max = tend;
                        }
                }
            } else {
                tend = i-1;
                in = false;
                int size = tend-tstart+1;
                if (!is_safe(tstart, tend, v))
                    if (size > max_size) {
                        max_size = size;
                        start_max = tstart;
                        end_max = tend;
                    }
            }
        } else {
            if (v[i] == 0) {
                in = true;
                tstart = i;
            }
            if (i == v.size() - 1) { // last element
                tend = i;
                int size = tend-tstart+1;
                if (!is_safe(tstart, tend, v))
                    if (size > max_size) {
                        max_size = size;
                        start_max = tstart;
                        end_max = tend;
                    }
            }
        }
    }

    if (start_max == 0) {
        return end_max;
    } else if (end_max == v.size()-1) {
        return start_max;
    } else if (v[start_max-1] == -1) {
        return end_max;
    } else {
        return start_max;
    }
}

void solve() {
    int n;
    int zeros=0;
    string s;
    vector<int> cities;
    cin >> n;
    cin >> s;
    FOR(i,0,s.length()-1) {
        if (s[i] == '1') {
            cities.PB(1);
        } else {
            cities.PB(0);
            zeros++;
        }
    }

    if (zeros == n) {
        cout << "0\n";
        return;
    }

    while(zeros > 0) {
        // FOR(i,0,cities.size()-1) cout << cities[i] << " ";cout << '\n';
        int vidx = vaccination_index(cities);
        if (vidx != -1) {
            cities[vidx] = -1;
            zeros--;
            
        } else {
            break;
        }
        zeros -= infect(cities);
    }
    cout << count_infected(cities) << '\n';
}

int main() {
    fix_io();
    UINT t;
    cin >> t;
    while(t--)
        solve();
}