/* 
*   @author:- SYEDA SADIATUL JANNAT TUSHI
*   date & time :2024-10-29 06:14:08
*   BANGLADESH , SYLHET. 
*/

#include <bits/stdc++.h>
using namespace std;
#define fi first
#define se second
#define endl '\n'
#define ll long long
#define ull unsigned long long
#define ld long double
#define PI acos(-1.0)
#define pb push_back
#define mp make_pair
#define vi vector<ll>
#define maxn 500005
#define mod 1000000007
#define inf 1000000007
#define pii pair<ll,ll>
#define vii vector<pii>
#define sz(x) (int)x.size()
#define all(x) x.begin(), x.end()
#define lcm(a,b) ((a*b)/__gcd(a,b));
#define srt(v) sort(v.begin(),v.end())
#define rsrt(v) sort(v.rbegin(),v.rend())
#define setbits(x) __builtin_popcountll(x)
#define rep(i, a, b) for(ll i = (a); i < (b); i++)
#define per(i, a, b) for(int i = (a); i >= (b); i--)
#define rev_str(str) reverse(str.begin(),str.end());
#define print(v) for(auto e:v) cout<<e<<" "; cout<<endl;
#define sum(a) (accumulate((a).begin(), (a).end(), 0LL))
#define printp(v) for(auto e:v) cout<<e.first<<" "<<e.second<<endl;
#define fast ios_base::sync_with_stdio(false);cin.tie(0);cout.tie(0);
bool sortByValue(const pair<int, int>& a, const pair<int, int>& b) {return a.second > b.second;}

string flip(const string& s) {
    string result = s;
    for (char& c: result) {
        c =(c == '0') ? '1' : '0';
    }
    return result;
}

void solve(){
   int n;cin>>n;
   string s;
   cin>>s;

   int mx=0,cnt=0;

   string p=flip(s);

   for(char c:p){
    if(c=='1'){
        cnt++;
        mx=max(mx,cnt);
    }
    else{
        cnt=0;
    }
   }
   cout<< mx <<endl;
}

int main() {
    fast
    ll t=1;cin>>t;
    while (t--) {
        solve();
    }
    return 0;
}