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import math
import sys

from collections import deque


def bfs(n, graph, start):
  dist = [math.inf] * n
  dist[start] = 0
  q = deque([start])
  while q:
    u = q.popleft()
    for (v, c) in graph[u]:
      if dist[v] > dist[u] + c:
        dist[v] = dist[u] + c
        if c == 1:
          q.append(v)
        else:
          q.appendleft(v)

  max_d = max(dist)
  furthest = dist.index(max_d)

  return max_d, furthest


def graph_diameter(n, graph):
  _, furthest1 = bfs(n, graph, 0)
  ans, _ = bfs(n, graph, furthest1)
  return ans


def solve():
  n = int(sys.stdin.readline())

  g = [[] for _ in range(n)]
  for u in range(n):
    for v, c in enumerate(sys.stdin.readline()):
      if c == '1':
        g[u].append((v, 1))

  ans = graph_diameter(n, g)

  for u in range(n):
    for v in range(u + 1, n):
      g[u].append((v, 0))
      g[v].append((u, 0))
      ans = min(ans, graph_diameter(n, g))
      g[u].pop()
      g[v].pop()

  print(ans)


def main():
  for _ in range(int(sys.stdin.readline())):
    solve()


if __name__ == "__main__":
  main()