#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using ld = long double;
#define pb push_back
#define mod 1000000007
#define srt(v) sort(v.begin(),v.end())
#define rsrt(v) sort(v.rbegin(),v.rend())
#define OPTIMIZE_IO ios::sync_with_stdio(false); cin.tie(nullptr);

void solve() {
    int n;
    cin>>n;
    string str;
    cin>>str;
    for(int i=0; i<str.size();i++){
        if(str[i]=='0'){
            str[i]='1';
        }
        else{
            str[i]='0';
        }
    }

    ll ans=0,count=0;
    for(auto it: str){
        if(it=='1'){
            count++;
            ans=max(ans,count);
        }
        else{
            count=0;
        }
    }
    cout<<ans<<endl;

}

int main() {
    OPTIMIZE_IO;
    int t;
    cin>>t;
    while (t--) {
        solve();
    }
    return 0;
}