#include <bits/stdc++.h>
using namespace std;
#define ZORO  ios::sync_with_stdio(false); cin.tie(0); cout.tie(0);
#define endl "\n"
#define int long long
const int M = 3e5 + 5, MOD = 998244353;

int gcd(int a,int b)
{
    while(b != 0)
    {
        int temp = a % b;
        a = b;
        b = temp;
    }
    return a;
}


void solve(){
    int n;
    cin>>n;
    string s;
    cin>>s;
    int ans = 0;
    int left = 0,right = 0;
    for(int i=0; i<n ;i++){
        if(s[i] == '0'){
            right++;
            int mx = right - left;
            ans = max(ans,mx);
        }
        else{
            left = i;
            right = i;
        }
    }
    cout<<ans<<endl;
}

int32_t main()
{

    ZORO
    int tt;
    cin>>tt;
    while(tt--)
    {
        solve();
    }

    return 0;
}