#define _GLIBCXX_FILESYSTEM
#include<bits/stdc++.h>
using namespace std;
#define ll long long

void solve() {
    int n;
    string s;
    cin >> n >> s;
    int cnt = 0, ans = 0;
    for(int i = 0; i < n; i++) {
        if(s[i] == '0') cnt++;
        else {
            ans = max(ans,cnt);
            cnt = 0;
        }
    }
    ans = max(ans, cnt);
    cout << ans << '\n';
    return;
}

int32_t main() {
    ios_base::sync_with_stdio(false);cin.tie(NULL);
    int tc = 1;
    cin >> tc;
    for(int kase = 1; kase <= tc; kase++) {
        //cout << "Case " << kase << ": ";
        solve();
    }
    return 0;
}