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

using ll = long long;
using lld = long double;
using ull = unsigned long long;
const ll mod=1000000007;


#define vr(v) v.begin(),v.end()
#define rv(v) v.end(),v.begin()
#define nline "\n"

ll gcd(ll a, ll b){if (b == 0)return a;return gcd(b, a % b);} //__gcd
ll lcm(ll a, ll b){return (a/gcd(a,b)*b);} // lcm

bool assen(const pair<int,int> &a,const pair<int,int> &b){return (a.second < b.second);}
bool desen(const pair<int,int> &a,const pair<int,int> &b){return (a.second > b.second);}

bool isPrime(ll n){if(n<=1)return false;if(n<=3)return true;if(n%2==0||n%3==0)return false;for(int i=5;i*i<=n;i=i+6)if(n%i==0||n%(i+2)==0)return false;return true;}


void solve(){
    int n;
    cin>>n;
    string s;
    cin>>s;
    int cn = 0,ans =0;
    for (int i=0;i<n;i++){
        if(s[i] == '1'){
            cn++;
            ans =max(cn,ans);
        }
        else{
            cn =0;
        }
    }
    cout<<ans<<nline;
}



int main(){
    ios_base::sync_with_stdio(false);
    cin.tie(NULL); cout.tie(NULL);
    int test_case=1;  cin>>test_case;
    while(test_case--){
        solve();
    }
    return 0;
}