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#include <iostream>
#include <vector>
#include <queue>
#include <algorithm>
#include <climits>

using namespace std;

int bfs(const vector<vector<int>>& adj, int start, int n) {
    vector<int> dist(n, INT_MAX);
    queue<int> q;
    q.push(start);
    dist[start] = 0;

    while (!q.empty()) {
        int u = q.front();
        q.pop();

        for (int v = 0; v < n; ++v) {
            if (adj[u][v] && dist[v] == INT_MAX) {
                dist[v] = dist[u] + 1;
                q.push(v);
            }
        }
    }

    return *max_element(dist.begin(), dist.end());
}

int main() {
    int t;
    cin >> t;

    while (t--) {
        int n;
        cin >> n;
        vector<vector<int>> adj(n, vector<int>(n));

        for (int i = 0; i < n; ++i) {
            string s;
            cin >> s;
            for (int j = 0; j < n; ++j) {
                adj[i][j] = s[j] - '0';
            }
        }

        int min_bak = INT_MAX;

        for (int u = 0; u < n; ++u) {
            for (int v = u + 1; v < n; ++v) {
                if (adj[u][v]) {
                    vector<vector<int>> temp_adj = adj;
                    temp_adj[u][v] = 0;
                    temp_adj[v][u] = 0;

                    int max_dist = 0;
                    for (int i = 0; i < n; ++i) {
                        int dist = bfs(temp_adj, i, n);
                        if (dist > max_dist) {
                            max_dist = dist;
                        }
                    }

                    if (max_dist < min_bak) {
                        min_bak = max_dist;
                    }
                }
            }
        }

        cout << min_bak << endl;
    }

    return 0;
}