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//  Created by Michal Kowalski on 07/12/2021.
//

#include <iostream>
#include <map>
#include <unordered_map>
#include <vector>
#include <algorithm>

int N;

inline int takefrom1(std::vector<std::pair<int, int>> & V1, int day) {
    // take only one sided group
    int len = V1[0].first - (day - 1);
    --V1[0].second;
    if (V1[0].second == 0) {
        V1.erase(V1.begin());
    }
    return len;
}

inline int takefrom2(std::vector<std::pair<int, int>> & V1, std::vector<std::pair<int, int>> & V2,int day) {
    int len = V2[0].first - (day - 1) * 2;
    int count = V2[0].second;
    --count;
    --len;
    if (count == 0) {
        V2.erase(V2.begin());
    } else {
        V2[0].second = count;
    }
    if (len > 0) {
        V1.insert(V1.begin(), {len, 1});
    }
    return 1;
}

int main(int argc, const char * argv[]) {
    scanf("%d",&N);
    for (int i=0;i<N;++i) {
        int K;
        scanf("%d",&K);
        char S[K+1];
        scanf("%s",S);
        // maps
        std::unordered_map<int, int> M2;
        std::unordered_map<int, int> M1;
        // read from input
        int lastIndex = -1;
        for (int j=0;j<K;++j) {
            if (S[j] == '1') {
                if (lastIndex == -1) {
                    if (j>0) {
                        int len = j;
                        //std::cout << "x" <<std::string(len, '0') << std::endl;
                        if (M1.find(len) != M1.end()) {
                            M1[len] = M1[len] + 1;
                        } else {
                            M1[len] = 1;
                        }
                    }
                } else {
                    if (j - lastIndex > 1) {
                        int len = j-lastIndex-1;
                        //std::cout << std::string(len, '0') << std::endl;
                        if (M2.find(len) != M2.end()) {
                            M2[len] = M2[len] + 1;
                        } else {
                            M2[len] = 1;
                        }
                    }
                }
                lastIndex = j;

            }
        }
        // no infection go to next test case
        if (lastIndex == -1) {
            printf("0\n");
            continue;
        }
        if (lastIndex < K && K-lastIndex > 1) {
            int len = K-lastIndex-1;
            //std::cout << std::string(len, '0') << "x" << std::endl;
            if (M1.find(len) != M1.end()) {
                M1[len] = M1[len] + 1;
            } else {
                M1[len] = 1;
            }
        }

        // for both sided groups
        std::vector<std::pair<int, int>> V2;
        V2.reserve(M2.size());
        for (const auto &[len, count] : M2) {
            //std::cout << count << " x " << len << "\n";
            V2.push_back({len, count});
        }
        std::sort(V2.begin(), V2.end(), std::greater<std::pair<int, int>>());

        // for one sided groups
        std::vector<std::pair<int, int>> V1;
        V1.reserve(M1.size());
        for (const auto &[len, count] : M1) {
            //std::cout << count << " x " << len << "\n";
            V1.push_back({len, count});
        }

        std::sort(V1.begin(), V1.end(), std::greater<std::pair<int, int>>());

        int day = 1;
        int vacc = 0;
        while (!V1.empty() || !V2.empty()) {
            if (V2.empty()) {
                vacc += takefrom1(V1, day);
            } else if (V1.empty()) {
                vacc += takefrom2(V1, V2, day);
            } else { // items in both queues
                int len1 = V1[0].first - (day - 1);
                int len2 = V2[0].first - (day - 1) * 2;
                if (len2 - 2 > len1 - 1) {
                    vacc += takefrom2(V1, V2, day);
                } else {
                    vacc += takefrom1(V1, day);
                }
            }

            //make infections
            if ((V2.rbegin() != V2.rend()) && (*V2.rbegin()).first <= day*2) V2.pop_back();
            if ((V2.rbegin() != V2.rend()) && (*V2.rbegin()).first <= day*2) V2.pop_back();

            std::sort(V1.begin(), V1.end(), std::greater<std::pair<int, int>>());
            while(!V1.empty() && (*V1.rbegin()).first <= day) V1.pop_back();

            ++day;
        }
        printf("%d\n",K-vacc);
    }
    return 0;
}