/*
 * @author Md. Fahmidur Rahman Nafi
 * @create date 05-11-2024    21:17:29
 */


#include <bits/stdc++.h>
using namespace std;
#define endl '\n'
#define ll long long
#define ld long double
#define ull unsigned long long
#define lcm(a,b) ((a*b)/__gcd(a,b))
const int MOD = 1000000007;

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

    int zero = count(s.begin(), s.end(), '0');
    int one = count(s.begin(), s.end(), '1');

    if (n == one){
        cout << 0 << endl;
        return;
    } 
    else if (n == zero){
        cout << n << endl;
        return;
    }
    
    int seq = 0;
    int count = 0;
    for (int i = 0; i < n; i++){
        if (s[i] == '0'){
            seq++;
        }
        else{
            seq = 0;
        }
        count = max(seq, count);
    }
    cout << count << endl;
}

int main(){
    ios_base::sync_with_stdio(false);
    cin.tie(0);

    int t;
    cin >> t;

    while(t--){
        solve();
    }    
}