#include<bits/stdc++.h>
#include<ext/pb_ds/assoc_container.hpp>
#include<ext/pb_ds/tree_policy.hpp>
using namespace __gnu_pbds;
using namespace std;
template <typename T> using pbds = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
#define ll long long
#define hello() ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
#define nl "\n"
#define yes cout<<"YES"<<nl
#define no cout<<"NO"<<nl
#define ss second
#define ff first
#define all(v) v.begin(),v.end()
#define eb emplace_back
#define sz(x) (int)(x).size()
#define pb push_back
#define mod 1000000007
#define mem(a,x) memset(a,x,sizeof(a))
int bit(ll a,int i){if(a&(1LL<<i)) return 1;return 0;}
int dx[]={1,-1,0,0,1,1,-1,-1};
int dy[]={0,0,1,-1,1,-1,1,-1};
ll isqrt (ll x){ll ans = 0;for (ll k = 1LL << 30; k != 0; k /= 2){if ((ans + k) * (ans + k) <= x) {ans += k;}}return ans;}
ll bin(ll n,ll pow){ll result=1;while(pow){if(pow&1){result=(result * n);}n=(n*n);pow>>=1;}return result;}
ll binmod(ll a,ll b,ll MOD){ll ans=1;a%=MOD;while(b){if(b&1)ans=(ans*a)%MOD;b/=2;a=(a*a)%MOD;}return ans;}
ll inverse(ll a,ll MOD){return binmod(a,MOD-2,MOD);}
const int N=500+12;
const  int M=998244353;

void solve(){
   
   int n;string s;
   cin>>n>>s;
   int i=0,j=0,cnt=0,ans=0;
   while(j<n){
    if(s[j]=='0')cnt++;
    else cnt=0;
    ans=max(ans,cnt);j++;
   }
   cout<<ans<<nl;
}

int main()
{
    hello();
cout.precision(10); cout.setf(ios::fixed);

    int tc;
    cin>>tc;
  for(int j=1;j<=tc;j++){
    //cout<<"Case #"<<j<<": ";
       solve();
   }
}