#include <bits/stdc++.h>
using namespace std;
int main()
{
    int t;
    cin >> t;
    while (t--)
    {
        int n;
        cin >> n;
        string str;
        cin >> str;
        vector<char> v;
        for (int i = 1; i < n; i++)
        {
            if (str[i] == '1')
            {
                v.push_back(str[i]);
            }
        }
        cout << v.size() << endl;
    }

    return 0;
}