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

void solve()
{
    ll n;
    cin >> n;
    string s;
    cin>>s;
    ll ans = 0, c = 0;
    for(int i = 0; i < n; i++){
        if(s[i] == '1')c++;
        else{
            ans = max(ans, c);
            c = 0;
        }
    }
    cout<<ans<<endl;
}
int main()
{
    int tc = 1, cs = 1;
    cin >> tc;
    while (tc--)
    {
        // cout<<"Case "<<cs<<": ";
        solve();
    }
    return 0;
}