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


void ks_2(){
    int n; cin >> n;
    string str; cin >> str;
    int mxCnt = 0;
    int currCnt = 0;
    for(auto it : str){
        if(it == '1'){
            currCnt = currCnt + 1;
            mxCnt = max(mxCnt, currCnt);
        }
        else currCnt = 0;
    }
    cout << mxCnt <<"\n";
}

int main(){
    int t; cin >> t;
    while(t--){
        ks_2();
    }

    return 0;
}