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import math

t = int(input())
results = []

for _ in range(t):
    n = int(input())
    adj_matrix = []
    for _ in range(n):
        row = input().strip()
        adj_matrix.append([int(c) for c in row])
    distance = [[math.inf] * n for _ in range(n)]
    for i in range(n):
        distance[i][i] = 0
        for j in range(n):
            if adj_matrix[i][j] == 1:
                distance[i][j] = 1

    for k in range(n):
        for i in range(n):
            for j in range(n):
                if distance[i][j] > distance[i][k] + distance[k][j]:
                    distance[i][j] = distance[i][k] + distance[k][j]

    min_max_distance = math.inf
    for u in range(n):
        for v in range(n):
            if u == v:
                continue
            current_max = 0
            for i in range(n):
                for j in range(n):
                    if i == j:
                        continue
                    d = min(distance[i][j], distance[i][u] + distance[v][j], distance[i][v] + distance[u][j])
                    if d > current_max:
                        current_max = d

            if current_max < min_max_distance:
                min_max_distance = current_max

    results.append(min_max_distance)

for result in results:
    print(result)