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#define debug 0

#include <bits/stdc++.h>

#define fastio() ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
#define perf  1
#define st first
#define nd second
#define remin(a,b) a=min(a,b);
#define remax(a,b) a=max(a,b);
#define mod 998244353
//#define mod 1'000'000'007


using namespace std;
const int inf = 1e8;
int n;
vector<vector<int>> m, kra, dist, rdist;

void bfs(int source) {
	dist[source][source] = 0;
	queue<int> q;
	q.push(source);
	while (!q.empty()) {
		int cur = q.front();
		q.pop();
		for (int next : kra[cur]) {
			if (dist[source][next] == inf) {
				dist[source][next] = dist[source][cur] + 1;
				q.push(next);
			}
		}
	}
}

void solve() {
	cin >> n;
	m.assign(n, vector<int>(n));
	dist.assign(n, vector<int>(n, inf));
	rdist.assign(n, vector<int>(n, inf));
	kra.assign(n, {});
	for (int i = 0; i < n; ++i) {
		for (int j = 0; j < n; ++j) {
			char c;
			cin >> c;
			m[i][j] = c - '0';
			if (m[i][j] == 1) {
				kra[i].emplace_back(j);
			}
		}
	}
	//do a bfs for every source
	for (int i = 0; i < n; ++i)
		bfs(i);

	for (int i = 0; i < n; ++i) {
		for (int j = 0; j < n; ++j) {
			rdist[i][j] = min(dist[i][j], max(dist[i][0], dist[0][j])); //real dist, bo mozemy tankowac
		}
	}

	if (debug) {
		for (int i = 0; i < n; ++i) {
			for (int j = 0; j < n; ++j) {
				cerr << rdist[i][j] << ' ';
			}
			cerr << '\n';
		}
	}

	int ans = inf;

	for (int u = 0; u < n; ++u) {
		for (int v = 0; v < n; ++v) { //tunel pomiedzy u-v
			//przetestuj kazde polaczenie
			int mx = -inf;
			for (int i = 0; i < n; ++i) {
				for (int j = 0; j < n; ++j) {
					int path=inf;
					remin(path, rdist[i][j]); //bez tunely
					remin(path, max(rdist[i][u], rdist[v][j])); //z tunelem
					remax(mx, path);
				}
			}
			remin(ans, mx);
		}
	}
	cout << ans << '\n';
}

int main() {
	fastio();
	int t=1;
	cin >> t;

	while (t--) {
		solve();
	}
	return 0;
}