#include<bits/stdc++.h>
using namespace std;
int main(){
    int T; cin>>T; while(T--){
        int N; string S;
        cin>>N>>S;
       int  count = 0;
       int mx_count = 0;
       for(int i = 0; i<N; i++){
        if(S[i]=='1'){ count++;
        mx_count = max(count,mx_count);
        }
        else if(S[i]=='0') count = 0;
       }
       cout<<mx_count<<endl;
    }
    
}