#include<bits/stdc++.h>
using namespace std; 
char nl = '\n';
using i64 = long long;

void solve(int t) {
    // cout << "test #" << t << nl;
    int n; cin >> n;
    string str; cin >> str;
    int mx = 0, cur = 0;
    for (int i = 0; i < n; i++) {
        mx = max(mx, cur);
        if (str[i] == '0') cur++;
        else {
            cur = 0;
        }
    }
    mx = max(mx, cur);
    cout << mx << nl;
}   

int main() {
    int tt = 1;
    cin >> tt;
    for(int t = 1; t <= tt; t++) solve(t);
}