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#include <bits/stdc++.h>

using namespace std;

#define rep(i, n) for(int i = 0; i < n; i++)
#define pb push_back
#define debug(x) cout << #x << " " << x << endl
#define all(x) x.begin(),x.end()
#define ll long long
#define vi vector<int>
#define vvi vector<vi>
#define vvvi vector<vvi>
#define vll vector<ll>
#define vvll vector<vll>
#define ld long double
#define ull unsigned long long
#define vull vector<ull>
#define fi first
#define se second
#define PII pair<int,int>
#define vPII vector<PII>
#define getunique(v) {sort(v.begin(), v.end()); v.erase(unique(v.begin(), v.end()), v.end());}
#define int128 __int128

int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
//    cout << setprecision(16) << fixed;
//    freopen("input.txt", "r", stdin);
//    freopen("output.txt", "w", stdout);
    int tt = 1;
    cin >> tt;
    while(tt--) {
        int n; string s;
        cin >> n >> s;
        vi dz;
        int pocz = 0, kon = 0;
        int j = 0;
        int cur = 0;
        while(j < n and s[j] == '0') j++;
        pocz = j;
        for(int i = j; i < n; i++){
            if(s[i] == '1'){
                if(cur){
                    dz.pb(cur);
                }
                cur = 0;
            }else{
                cur++;
            }
        }
        kon = cur;
        sort(all(dz));
        reverse(all(dz));
        int str = 1;
        int ans = 0;
        int cnt = 0;
        for(int x: dz){
            if(x-str <= 0) break;
            cnt++;
            ans += max(0,x-str);
            str += 4;
        }
        if(kon > pocz) swap(pocz,kon);
        ans += max(0,pocz-cnt*2);
        ans += max(0,kon-cnt-1);

        cout << n - ans << "\n";
    }
}