1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
#define pb push_back
#define mp make_pair
#define all(a) begin(a),end(a)
#define FOR(x,val,to) for(int x=(val);x<int((to));++x)
#define FORE(x,val,to) for(auto x=(val);x<=(to);++x)
#define FORR(x,arr) for(auto &x: arr)
#define FORS(x,plus,arr) for(auto x = begin(arr)+(plus); x != end(arr); ++x)
#define FORREV(x,plus,arr) for(auto x = (arr).rbegin()+(plus); x !=(arr).rend(); ++x)
#define REE(s_) {cout<<s_<<'\n';exit(0);}
#define GET(arr) for(auto &i: (arr)) sc(i)
#define whatis(x) cerr << #x << " is " << (x) << endl;
#define e1 first
#define e2 second
#define INF 0x7f7f7f7f
typedef std::pair<int,int> pi;
typedef std::vector<int> vi;
typedef std::vector<std::string> vs;
typedef int64_t ll;
typedef uint64_t ull;
#define umap unordered_map
#define uset unordered_set
using namespace std;
using namespace __gnu_pbds;

#ifdef ONLINE_JUDGE
#define whatis(x) ;
#endif
#ifdef _WIN32
#define getchar_unlocked() _getchar_nolock()
#define _CRT_DISABLE_PERFCRIT_LOCKS
#endif
template<class L, class R> ostream& operator<<(ostream &os, map<L, R> P) { for(auto const &vv: P)os<<"("<<vv.first<<","<<vv.second<<")"; return os; }
template<class T> ostream& operator<<(ostream &os, set<T> V) { os<<"[";for(auto const &vv:V)os<<vv<<","; os<<"]"; return os; }
template<class T> ostream& operator<<(ostream &os, vector<T> V) { os<<"[";for(auto const &vv:V)os<<vv<<","; os<<"]"; return os; }
template<class L, class R> ostream& operator<<(ostream &os, pair<L, R> P) { os<<"("<<P.first<<","<<P.second<<")"; return os; }
inline int fstoi(const string &str){auto it=str.begin();bool neg=0;int num=0;if(*it=='-')neg=1;else num=*it-'0';++it;while(it<str.end()) num=num*10+(*it++-'0');if(neg)num*=-1;return num;}
inline void getch(char &x){while(x = getchar_unlocked(), x < 33){;}}
inline void getstr(string &str){str.clear(); char cur;while(cur=getchar_unlocked(),cur<33){;}while(cur>32){str+=cur;cur=getchar_unlocked();}}
template<typename T> inline bool sc(T &num){ bool neg=0; int c; num=0; while(c=getchar_unlocked(),c<33){if(c == EOF) return false;} if(c=='-'){ neg=1; c=getchar_unlocked(); } for(;c>47;c=getchar_unlocked()) num=num*10+c-48; if(neg) num*=-1; return true;}template<typename T, typename ...Args> inline void sc(T &num, Args &...args){ bool neg=0; int c; num=0; while(c=getchar_unlocked(),c<33){;} if(c=='-'){ neg=1; c=getchar_unlocked(); } for(;c>47;c=getchar_unlocked()) num=num*10+c-48; if(neg) num*=-1; sc(args...); }
template<typename T> using ordered_set = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>; //s.find_by_order(), s.order_of_key() <- works like lower_bound
template<typename T> using ordered_map = tree<T, int, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
#define N 1000001

int main(){
    ios_base::sync_with_stdio(0);cin.tie(0);
    int t;
    sc(t);
    while(t--){
        int n;
        sc(n);
        string s;
        getstr(s);
        vector<int> a;
        int cnt = 0;
        FORR(i,s){
            /* if(i == '0'){ */
            if(i == '1'){
                /* if(cnt) */
                a.push_back(cnt);
                cnt = 0;
            }
            else{
                ++cnt;
            }
        }
        /* if(cnt) */
        a.push_back(cnt);
        if(a.size() == 1){
            /* cout << n << '\n'; */
            cout << "0\n";
            continue;
        }
        vi type1, type2;
        type1.push_back(a.front());
        type1.push_back(a.back());
        type2 = std::move(a);
        type2.pop_back();
        type2.erase(type2.begin());
        vector<pi> vec;
        FORR(i,type1)
            vec.emplace_back(1, i);
        FORR(i,type2)
            vec.emplace_back(2, i);
        // raczej x2 a nie sq xd.
        /* sort(all(vec), [](auto &f, auto &s){return f.e1 == s.e1 ? f.e2 > s.e2 : f.e1 == 1 ? f.e2 * f.e2 >= s.e2 : f.e2 > s.e2 * s.e2;}); */
        sort(all(vec), [](auto &f, auto &s){return f.e1 == s.e1 ? f.e2 > s.e2 : f.e1 == 1 ? f.e2 * 2 >= s.e2 : f.e2 > s.e2 * 2;});
        reverse(all(vec));
        int res = 0;
        while(vec.size()){
            int ile = 1;
            if(vec.back().e2 <= 0)
                break;
            if(vec.back().e1 == 1){
                res += vec.back().e2;
            }
            else{
                if(vec.back().e2 <= 2){
                    ++res;
                }
                else{
                    ile = 2;
                    res += vec.back().e2 - 1;
                }
            }
            vec.pop_back();
            FOR(_,0,ile){
                /* FORR(i,vec){ */
                for(int x = vec.size() - 1; x >= 0; --x){
                    if(vec[x].e1 == 1)
                        --vec[x].e2;
                    else
                        ----vec[x].e2;
                    if(vec[x].e2 <= -2)
                        break;
                }
            }
        }
        /* cout << res << '\n'; */
        cout << n - res << '\n';
    }
}