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#include <iostream>
#include <algorithm>

#ifdef TEST_MODE
#include <fstream>
#endif

using namespace std;

const int kMaxCities = 100000;

int main() {
#ifdef TEST_MODE
    std::ifstream in("140.in"); std::cin.rdbuf(in.rdbuf());
#endif
    std::ios_base::sync_with_stdio(false);
    
    int hRanges[kMaxCities+1];
    int t;
    cin >> t;
    while ( t-- ) {
        int n;
        int noHealthyCities = 0;
        int days = 0;
        char cities[kMaxCities+1];
        int leftRange, rightRange;
        leftRange = rightRange = -1;
        cin >> n;
        for ( int i = 0; i < n; ++i ) {
            hRanges[i] = 0;
        }
        cin >> cities;
        int r = 0;
        for ( int i = 0; i < n; ++i ) {
            if ( cities[i] == '0' ){
                r++;
            } else {
                if ( leftRange < 0 ) {
                    leftRange  = r;
                } else if ( r > 0 ){
                    hRanges[r]++;
                }
                r = 0;
            }
        }
        rightRange = r;
        if ( n == 1 && rightRange == 1) {
            noHealthyCities = 1;
        }
        
        for ( int i = n - 1; i > days * 2; --i ) {
            if ( i - days * 2 <= (leftRange - days) * 2 ) {
                noHealthyCities += leftRange - days;
                leftRange = 0;
                days++;
            }
            if ( i - days * 2 <= (rightRange - days) * 2 ) {
                noHealthyCities += rightRange - days;
                rightRange = 0;
                days++;
            }
            
            if ( hRanges[i] > 0 ) {
                int td = (i - days * 2 + 1) / 4;
                int d = min(td, hRanges[i]);
                noHealthyCities += ((i - days * 2 - 1) + (i - days * 2 - (d - 1) * 4 - 1)) * d / 2;
                if ( td < hRanges[i] && ((i - days * 2) % 4 == 1 || (i - days * 2) % 4 == 2)) {
                    noHealthyCities++;
                    days++;
                }
                days += d * 2;
            }
        }
        
        cout << n - noHealthyCities << endl;
    }
    return 0;
}