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#include <iostream>
#include <queue>

const int N = 400 + 1;

char graph[N][N];
int dist[N][N];

void bfs(int u, int n) {
    std::vector visited(N + 1, false);
    std::queue<int> toVisit;
    toVisit.push(u);
    visited[u] = true;

    for (int i = 1; i <= n; i++) {
        dist[u][i] = N * 2;
    }
    dist[u][u] = 0;

    while(!toVisit.empty()) {
        auto visiting = toVisit.front();
        toVisit.pop();

        for (int i = 1; i <= n; i++) {
            if (graph[visiting][i] == '1' && !visited[i]) {
                toVisit.push(i);
                visited[i] = true;
                dist[u][i] = std::min(dist[u][visiting] + 1, dist[u][i]);
            }
        }
    }
}

int main() {
    std::ios_base::sync_with_stdio(0);
    std::cin.tie(0);

    int t;
    std::cin >> t;

    for (int testCase = 0; testCase < t; testCase++) {
        int n;
        std::cin >> n;

        for (int i = 1; i <= n; i++) {
            for (int j = 1; j <= n; j++) {
                std::cin >> graph[i][j];
            }
        }

        for (int i = 1; i <= n; i++) {
            bfs(i, n);
        }

        int bestMaxDist = N * 2;
        for (int t1 = 1; t1 <= n; t1++) {
            for (int t2 = t1 + 1; t2 <= n; t2++) {
                int maxDist = 0;
                for (int i = 1; i <= n; i++) {
                    for (int j = 1; j <= n; j++) {
                        int distance = std::min(dist[i][j], std::min(dist[i][t1] + dist[t2][j], dist[i][t2] + dist[t1][j]));
                        maxDist = std::max(maxDist, distance);
                    }
                }
                bestMaxDist = std::min(maxDist, bestMaxDist);
            }
        }

        std::cout << bestMaxDist << "\n";
    }

    return 0;
}