def flatlandSpaceStations(n, c):
    c = sorted(c)
    distances = []
    if n == 1:
        return 0
    if len(c) == 1:
        return max(c[0], n - c[0] - 1)
    for city in range(len(c)):
        print(city)
        if city == 0:
            distances.append(c[city])
        elif city == len(c) - 1:
            distances.append(n - c[city] - 1)
            break
        distances.append(abs(c[city] - c[city + 1]) // 2)
    return max(distances)