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

typedef long long ll;
#define bug(a) cout << #a << " : " << a << endl;

signed main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);

    int t = 1; cin >> t;
    while (t--) {
        int n; cin >> n;
        string s;cin>>s;
        int cur=0;
        int ans=0;
        for(int i=0;i<n;i++){
            if(s[i]=='1')cur++;
            else cur=0;
            ans=max(ans,cur);
        }
        cout<<ans<<endl;
    }
    return 0;
}