#include <bits/stdc++.h>
#define ll long long
#define pub push_back
#define fast                      \
    ios_base::sync_with_stdio(0); \
    cin.tie(0);
using namespace std;
void solve()
{
    int n;
    cin >> n;
    string s;
    cin >> s;
    int ans = 0;
    int cnt = 0;
    for (char c : s)
    {
        if (c == '0')
            cnt++;
        else
        {
            ans = max(ans, cnt);
            cnt = 0;
        }
    }
    ans = max(ans, cnt);
    cout << ans << endl;
}
int main()
{
    fast;
    ll t;
    cin >> t;
    while (t--)
    {
        solve();
    }
    return 0;
}