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#define make_pair mp
#define emplace_back pb
#include <bits/stdc++.h>
using namespace std;
mt19937 mt_rand(time(0));
const int N = 1e5 + 5;
int t, n;
char s[N];
multiset<int> S;
int main() {
	scanf("%d", &t);
    while(t--) {
        S.clear();
        scanf("%d", &n);
        scanf("%s", s);
        int first = 0;
        while(s[first] == '0') first++;
        int a = first;
        if(first == n) {
            a = -1;
        }
        for(int i=first + 1;i<n;i++) {
            if(s[i] == '1') {
                if(i != first + 1) S.insert(i - first - 1);
                first = i;
            }       
        }
        int b = n - first - 1;
        if(first == n) {
            b = -1;
        }
        if(a < b) swap(a, b);
        int time = 0;
        int res = 0;
        S.insert(0);
        while(true) {
            auto it = S.end();
            it--;
            int x = *it;
            if(2 * a >= x) {
                if(a - time <= 0) break;
                res += a - time;
                time++;
                a = -1;
            } else if(2 * b >= x) {
                if(b - time <= 0) break;
                res += b - time;
                time++;
                b = -1;
            } else {
                S.erase(it);
                x -= 2 * time;
                if(x == 1) {
                    res++;
                    break;
                }
                if(x <= 0) {
                    break;
                }
                res += x - 1;
                time += 2;
            }
        }
        if(first == n) {
            printf("0\n");
        } else printf("%d\n", n - res);
    }
	return 0;
}