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#include <iostream>
#include <queue>

int t, n;
std::priority_queue<int> m;
int start, end;

void input() {
    std::string s;
    std::cin >> n >> s;
    int k = 0;
    int i = 0;
    start = -1;
    end = -1;
    while (i < n) {
        if (s[i] == '0') {
            ++k;
        } else if (start == -1) {
            start = k;
            k = 0;
        } else if (k > 0) {
            m.push(k);
            k = 0;
        }
        ++i;
    }
    end = k;
}

int max(int i, int j) {
    return i > j ? i : j;
}

int solve(bool e, bool s) {
    std::priority_queue<int> Q = m;
    
    if (start == -1) {
        return 0;
    }

    int result = 0;
    int i = 0;
    if (e && end - i > 0) {
        result += end - i;
        ++i;
    }
    if (s && start - i > 0) {
        result += start - i;
        ++i; 
    }

    while (!Q.empty()) {
        int q = Q.top();
        Q.pop();
        int qq = q - 2 * i;
        int ii = 2;
        if (qq == 1) {
            ii = 1;
        } else {
            qq -= 1;
        }

        if (qq <= 0) {
            break;
        }

        result += qq;
        i += ii;
    }

    return n - result;
}

int min(int a, int b) {
    return a < b ? a : b;
}

int solve() {
    int res = min(
        min(solve(false, false), solve(false, true)), 
        min(solve(true, false), solve(true, true))
    );
    while (!m.empty()) {
        m.pop();
    }
    return res;
}

int main() {
    std::ios_base::sync_with_stdio(false);
    std::cin.tie(NULL);

    std::cin >> t;
    while (t--) {
        input();
        std::cout << solve() << "\n";
    }
    return 0;
}