static int flatlandSpaceStations(int n, int[] c) {
        Arrays.sort(c);
        int max = Math.max(c[0], n - 1 - c[c.length - 1]);
        for (int i = 1; i < c.length; i++) {
            max = Math.max(max, (c[i] - c[i - 1]) / 2);
        }
        return max;
    }