#include <bits/stdc++.h>
#define ll long long int
#define ld long double
#define pb push_back
#define mod 1000000007

using namespace std;

void solve()
{
    string s;
    ll l, i, mx=0, c=0;
    cin>> l >> s;
    for(i=0; i<l; i++)
    {
        if(s[i]=='1')   c=0;
        else    
        {
            c++;
            mx = max(mx, c);
        }
    }
    cout<< mx << '\n';
}

int main()
{
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
 
    ll T = 1, cs = 1, i, k=0;
    cin >> T;
    //sieve();
    //cin.get();

    while(T--)
    {
        //cout<< "Case " << cs++ << ": ";
        solve();
    }
    return 0;
}