#include <iostream>
#include <bits/stdc++.h>
using namespace std;
//
#define sandipon 1

// Speed
#define Code ios_base::sync_with_stdio(false);
#define By cin.tie(NULL);
#define Sandipon cout.tie(NULL);

// Aliases
using ll = long long;
using lld = long double;
using ull = unsigned long long;

// Constants
const lld pi = 3.141592653589793238;
const ll INF = LONG_LONG_MAX;
const ll mod = 1e9 + 7;

// TypeDEf
typedef pair<ll, ll> pll;
typedef vector<ll> vll;
typedef vector<pll> vpll;
typedef vector<string> vs;
typedef unordered_map<ll, ll> umll;
typedef map<ll, ll> mll;

// Macros
#define ff first
#define ss second
#define pb push_back
#define mp make_pair
#define fl(i, n) for(int i = 0; i < n; i++)
#define rl(i, m, n) for(int i = n; i >= m; i--)
#define py cout << "YES\n";
#define pm cout << "-1\n";
#define pn cout << "NO\n";
#define vr(v) v.begin(), v.end()
#define rv(v) v.end(), v.begin()

// Debug
#ifdef sandipon
#define dd(x) cerr <<   "show for only check "; cerr << #x << " "; cerr << x << " "; cerr << endl;
#else
#define dd(x);
#endif

// Operator overloads
template<typename T1, typename T2> // cin >> pair<T1, T2>
istream& operator>>(istream &istream, pair<T1, T2> &p) { return (istream >> p.first >> p.second); }
template<typename T> // cin >> vector<T>
istream& operator>>(istream &istream, vector<T> &v){for (auto &it : v)cin >> it;return istream;}
template<typename T1, typename T2> // cout << pair<T1, T2>
ostream& operator<<(ostream &ostream, const pair<T1, T2> &p) { return (ostream << p.first << " " << p.second); }
template<typename T> // cout << vector<T>
ostream& operator<<(ostream &ostream, const vector<T> &c) { for (auto &it : c) cout << it << " "; return ostream; }

// Utility functions
template <typename T>
void print(T &&t)  { cout << t << "\n"; }
void printarr(ll arr[], ll n){fl(i,n) cout << arr[i] << " ";cout << "\n";}
template<typename T>
void printvec(vector<T>v){ll n=v.size();fl(i,n)cout<<v[i]<<" ";cout<<"\n";}
template<typename T>
ll sumvec(vector<T>v){ll n=v.size();ll s=0;fl(i,n)s+=v[i];return s;}

// Mathematical functions
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);}
ll moduloMultiplication(ll a,ll b,ll mod){ll res = 0;a %= mod;while (b){if (b & 1)res = (res + a) % mod;b >>= 1;}return res;}
ll powermod(ll x, ll y, ll p){ll res = 1;x = x % p;if (x == 0) return 0;while (y > 0){if (y & 1)res = (res*x) % p;y = y>>1;x = (x*x) % p;}return res;}

// Sorting
bool sorta(const pair<int,int> &a,const pair<int,int> &b){return (a.second < b.second);}
bool sortd(const pair<int,int> &a,const pair<int,int> &b){return (a.second > b.second);}

// Bits
string decToBinary(int n){string s="";int i = 0;while (n > 0) {s =to_string(n % 2)+s;n = n / 2;i++;}return s;}
ll binaryToDecimal(string n){string num = n;ll dec_value = 0;int base = 1;int len = num.length();for(int i = len - 1; i >= 0; i--){if (num[i] == '1')dec_value += base;base = base * 2;}return dec_value;}

// Check
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;}
bool isPowerOfTwo(int n){if(n==0)return false;return (ceil(log2(n)) == floor(log2(n)));}
bool isPerfectSquare(ll x){if (x >= 0) {ll sr = sqrt(x);return (sr * sr == x);}return false;}

void solve()
{

    //start
    ll n;cin>>n;string s;cin>>s;
    ll t=(n+2-1)/2;
    ll ans=0;
    ll cnt=0;
    fl(i,n){
     if(s[i]=='0'){
        cnt++;
     }else{
      ans=max(ans,cnt);
      cnt=0;
     }
    }
     ans=max(ans,cnt);
 
     cout<<ans<<endl;


    // end
}
// Main
int main()
{
    Code By Sandipon



    int T;
    cin>>T;
    while(T--)
    {
        solve();
    }
     //solve();
    return 0;
}
// End