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

const int mod = 998244353;
const int inf = 1e17;
const int N = 1e5+5;

int32_t main(){
    cin.tie(0); cout.tie(0);
    ios_base::sync_with_stdio(false);
    int t;
    cin>>t;
    while(t--){
        int n;
        cin>>n;
        string s;
        cin>>s;
        int ans = 0, cnt = 0;
        for(int i = 0; i < n; i++){
            if(s[i] == '0'){
                cnt++;
                ans = max(ans, cnt);
            }
            else{
                cnt = 0;
            }
        }

        cout<<ans<<endl;
    }
    return 0;
}