#include <bits/stdc++.h>
using namespace std;
#define ll long long int

int maxLengthOfZeros(string& s) {
    int max_len = 0, current_len = 0;

    for (char ch : s) {
        if (ch == '0') {
            current_len++;
        } else {
            max_len = max(max_len, current_len);
            current_len = 0;
        }
    }
    max_len = max(max_len, current_len);
    
    return max_len;
}

void solve()
{
    ll n;
    cin >> n;
    string s;
    cin>>s;
    cout<<maxLengthOfZeros(s)<<endl;
}
int main()
{
    int tc = 1, cs = 1;
    cin >> tc;
    while (tc--)
    {
        // cout<<"Case "<<cs<<": ";
        solve();
    }
    return 0;
}