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

int main() {
	int t;	cin >> t;
	while(t--){
		ll n;
		cin >> n;
		string s;	cin >> s;
		ll one = 0, pone = 0;
		for(ll i=0;i<n;i++)	s[i] == '0' ? s[i] = '1' : s[i] = '0';
		for(ll i = 0;i<n;i++){
			if(s[i] == '1')	one++;
			else{
				pone = max(pone,one);
				one = 0;
			}
		}
		cout << max(pone,one) << endl;
	}
	return 0;
}