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#include <iostream>
#include <vector>
#include <climits>
#include <algorithm>
using namespace std;

const int max_cities = 400;
const int INF = INT_MAX;
vector<vector<int>> adj_list;
vector<pair<int, int>> edge_list;

void print_adj_matrix(int n, vector<vector<int>>& adj_matrix) {
    cout << "Macierz sąsiedztwa:\n";
    for (int i = 0; i < n; i++) {
        for (int j = 0; j < n; j++) {
            cout << adj_matrix[i][j] << " ";
        }
        cout << "\n";
    }
    cout << "\n";
}

void print_adj_list(int n) {
    cout << "Lista sąsiedztwa:\n";
    for (int i = 0; i < n; i++) {
        cout << "Miasto " << i + 1 << ": ";
        for (int neighbor : adj_list[i]) {
            cout << neighbor  << " ";
        }
        cout << "\n";
    }
    cout << "\n";
}

vector<pair<int, pair<int, int>>> table_of_furthest(vector<vector<int>> &matrix) {
    int n = matrix.size();
    vector<pair<int, pair<int, int>>> distances;

    for (int i = 0; i < n; i++) {
        for (int j = i + 1; j < n; j++) {
            distances.push_back({matrix[i][j], {i, j}});
        }
    }

    sort(distances.begin(), distances.end());
    return distances;
}

int find_max_distance(vector<vector<int>> &dist) {
    int n = dist.size();
    int max_distance = 0;
    for (int i = 0; i < n; i++) {
        for (int j = i+1; j < n; j++) {
            max_distance = max(max_distance, dist[i][j]);
        }
    }
    return max_distance;
}

void floyd_warshall_algo(vector<vector<int>> &matrix) {
    int n = matrix.size();
    for (int i = 0; i < n; i++) {
        for (int j = 0; j < n; j++) {
            for (int k = 0; k < n; k++) {
                if (matrix[i][k] != INF && matrix[k][j] != INF) {
                    matrix[i][j] = min(matrix[i][j], matrix[i][k] + matrix[k][j]);
                }
            }
        }
    }
}

void solve(int n,const vector<pair<int, int>>& edges) {
    // Create floyd-marshall
    vector<vector<int>> floyd_marshall(n, vector<int>(n, INF));
    for (int i = 0; i < n; i++) {
        for (int j = 0; j < n; j++) {
            if (i != j) {
                floyd_marshall[i][j] = INF;
            } else {
                floyd_marshall[i][j] = 0;
            }
        }
    }

    for (const auto& edge : edges) {
        int v1 = edge.first;
        int v2 = edge.second;
        floyd_marshall[v1][v2] = 1;
        floyd_marshall[v2][v1] = 1;
    }

    vector<vector<int>> floyd_basic = floyd_marshall;

    for (int k = 0; k < n; k++) {
        for (int i = 0; i < n; i++) {
            for (int j = 0; j < n; j++) {
                if (floyd_marshall[i][k] != INF && floyd_marshall[k][j] != INF &&
                    floyd_marshall[i][j] > floyd_marshall[i][k] + floyd_marshall[k][j]) {
                    floyd_marshall[i][j] = floyd_marshall[i][k] + floyd_marshall[k][j];
                    }
            }
        }
    }
    print_adj_matrix(n,floyd_marshall);
    vector<pair<int, pair<int, int>>> furthest_table = table_of_furthest(floyd_marshall);

    int prev_max_distance = INF;
    int max_distance = find_max_distance(floyd_marshall);
    int i = 0;

    while (prev_max_distance > max_distance) {
        prev_max_distance = max_distance;
        vector<vector<int>> floyd_teleport = floyd_basic;
        pair<int,int> furthest = furthest_table[i].second;
        floyd_teleport[furthest.first][furthest.second] = 0;
        floyd_teleport[furthest.second][furthest.first] = 0;
        floyd_warshall_algo(floyd_teleport);
        max_distance = find_max_distance(floyd_teleport);
        i++;
    }
    cout << max_distance << "\n";
}

int main() {
    // ios::sync_with_stdio(false);
    // cin.tie(nullptr);

    int t;
    cin >> t;

    while (t--) {
        int n;
        cin >> n;
        int adj_matrix[n][n];
        adj_list.assign(n, vector<int>()); // Reset

        for (int i = 0; i < n; i++) {
            string row;
            cin >> row;
            for (int j = 0; j < n; j++) {
                adj_matrix[i][j] = row[j] - '0';
                if (adj_matrix[i][j] == 1) {
                    adj_list[i].push_back(j);
                    edge_list.push_back({i, j});
                }
            }
        }
        solve(n,edge_list);
    }
    return 0;
}