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

/*#ifndef ONLINE_JUDGE
#include "DEBUG.h"
#define bug(...)           __f (#__VA_ARGS__, __VA_ARGS__)
#endif*/

#define first_in_out       ios_base::sync_with_stdio(false);cin.tie(NULL);cout.tie(NULL);
#define ll                 long long int
#define double             long double
#define min_heap           priority_queue <ll, vector<ll>, greater<ll>>
#define print(a)           for(auto x : a) cout << x << " ";
#define printpair(a)       for(auto x : a) cout << x.first << " " << x.second<<"\n";



void solve()
{
	int n;
	cin >> n;
	string s;
	cin >> s;
	int ans = 0;
	for (int i = 0; i < n; i++)
	{
		if (s[i] == '0')
		{
			int cnt = 0;

			while (i < n and s[i] == '0')
			{
				cnt++;
				i++;
			}
			ans = max(ans, cnt);
		}
	}

	cout << ans << "\n";
}


int main()
{
	first_in_out
	//clock_t z = clock();

	int t = 1;
	cin >> t;

	while (t--)
		solve();

	//cerr << "Run Time : " << ((double)(clock() - z) / CLOCKS_PER_SEC);
}