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

int main() {
  int t;
  cin >> t;
  while (t--){
    ll n, c = 0, ans = 0;
    string s;
    cin >> n >> s;
    s += '?';
    for (int i = 0; i <= n; i++){
        if (s[i] == '0') c++;
        else ans = max(ans, c), c = 0;
    }
    cout << ans << endl;
  }
}