#ifndef LOCAL
#include <bits/stdc++.h>
#define debug(...)
#endif

using namespace std;
#define int long long
#define cinv(v) for (auto &it:v) cin>>it;
#define coutv(v) for (auto &it:v) cout<< it<<' '; cout<<'\n';

void shelby() {
    int n;
    string s;
    cin >> n >> s;
    int ans = 0, now = 0;
    for (auto &it: s) {
        if (it == '1') {
            ans = max(ans, now);
            now = 0;
        }
        else now++;
        debug(ans, it, now);
    }
    ans = max(ans, now);
    cout << ans << '\n';
}

signed main() {
    cin.tie(0)->sync_with_stdio(0);
    int t = 1;
    cin >> t;
    for (int _ = 1; _ <= t; ++_) {
        // cout << "Case " << _ << ": ";
        shelby();
    }
}