function is_drivable(start, finish, grid):
    queue = [(start, 1)]  # start cell with probability 1
    visited = set()
    while queue is not empty:
        current_cell, prob = queue.pop(0)
        if current_cell == finish and prob >= 1 - 1e-100:
            return True  # finish cell reached with sufficient probability
        for next_cell in neighboring_cells(current_cell, grid):
            if next_cell not in visited:
                visited.add(next_cell)
                queue.append((next_cell, prob * 0.5))  # equal probability of misinterpretation
    return False  # finish cell not reachable with sufficient probability

# Main function
for each test case:
    R, C, grid = parse_input()
    drivable_pairs = []
    for start_cell in interesting_start_cells:
        for finish_cell in interesting_finish_cells:
            if is_drivable(start_cell, finish_cell, grid):
                drivable_pairs.append((start_cell, finish_cell))
    if len(drivable_pairs) == 0:
        print("Case #{}: NONE".format(test_case_number))
    else:
        sorted_drivable_pairs = sort_drivable_pairs(drivable_pairs)
        print("Case #{}: {}".format(test_case_number, " ".join(sorted_drivable_pairs)))