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

void solve() {
    int n;
    cin >> n;
    string s;
    cin >> s;
    string s1 = ""; 
    for (char c : s) {
        if (c == '0') {
            s1 += '1';
        } else {
            s1 += '0';
        }
    }

    int mx=0,cnt=1;
    for(int i=0; i<s1.size(); i++){
        if(s1[i]=='1' && s1[i+1]=='1'){
            cnt++;
            if(cnt>mx){
                mx=cnt;
            }
        }
        else cnt=1;
    }
    cout<<mx<<endl;
}

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