#include <bits/stdc++.h>
using namespace std;
int main()
{
    int t;
    cin >> t;
    while (t--)
    {
        int n;
        cin >> n;
        string str;
        cin >> str;

        vector<int> ones;
        vector<int> zeros;
        int d = 0;
        for (int i = 0; i < n; i++)
        {
            if (str[i] == '1')
            {
                ones.push_back(i);
            }
            else
            {
                zeros.push_back(i);
            }
        }

        int mO = ones.size();
        int mZ = zeros.size();
        int operations_ones = 0;
        for (int j = 0; j < mO; j++)
        {
            operations_ones += abs(ones[j] - j);
        }

        for (int i = 0; i < mZ; i++)
        {
            d = d + abs(zeros[i] - i);
        }

        cout << min(operations_ones, d) << endl;
    }

    return 0;
}