#include <bits/stdc++.h>
using namespace std;

#define ll long long int
#define ld long double
#define endl '\n'
#define MIR183_PC ios_base::sync_with_stdio(false); cin.tie(NULL); cout.tie(NULL);
#define yes cout << "YES" << endl
#define no cout << "NO" << endl

void solve() {
    // Your code here
        ll n;
        string s;
        cin>>n>>s;
        vector<ll>zv;
        ll czero=0;
        
        for (ll i=0;i<n;i++){
            if (s[i]=='0'){
                czero++;
            }
            else{
                if(czero>0)zv.push_back(czero);
                czero=0;
            }
        }
        if (czero>0)zv.push_back(czero);
        

        
        sort(zv.rbegin(),zv.rend());
        if(!zv.empty())cout<<zv[0]<<endl;
        else cout<<0<<endl;
}

signed main() {
    MIR183_PC;
    // Always use ll, int may give TLE
    ll tt;
    // tt=1;
    cin >> tt;
    while (tt--) {
        solve();
    }
    return 0;
}