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

void solve() {
    long long n;
    cin>>n;
    string s;
    cin>>s;

    string s1 = ""; 
    for(char c:s) {
        s1+=(c=='0') ?'1':'0';
    }
    long long mx= 0, count = 0;
    for (char c : s1){
        if (c=='1'){
            count++;
            mx=max(mx, count);
        } else {
            count=0;
        }
    }
    cout<<mx<<endl;
}

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