//on the name of Allah:)
#include<bits/stdc++.h>
#define int         long long
#define Endl        "\n"
#define pi          2 * acos(0.0)
#define mod         1000000007
#define Mul(a,b)    (a%mod * b%mod)%mod
#define Add(a,b)    (a%mod + b%mod)%mod
#define all(x)      (x).begin(),(x).end()
#define allr(x)     (x).rbegin(),(x).rend()
#define gcd(x, y)   (__gcd(x, y))
#define lcm(x, y)   ((x/gcd(x, y))*y)
#define faster      cin.tie(NULL), cout.tie(NULL);
#define TC          int t ; cin>>t ; for(int i=1;i<=t;i++)
const int N = 1e6 + 7;
using namespace std;
void s()
{
    int n;
    cin>>n;
    string s;
    cin>>s;
     int maxCount = 0;
    int currentCount = 0;
    int z=0;
     for (int i=0;i<n;i++)
     {
         if(s[i]=='0')s[i]='1';
         else s[i]='0';
     }

    for (int i=0;i<n;i++) {
        if (s[i] == '1') {
            currentCount++;
            maxCount = max(maxCount, currentCount);
        } else {
            currentCount = 0;
            z++;
        }
    }
   cout<<maxCount<<endl;

}



int32_t main()
{
    ios::sync_with_stdio(false);
    //faster
 TC
    {
        //cout<<"Case "<<i<<": ";
        s();

    }



}