Average of 3 long integers

This code will work, but isn’t that pretty.

It first divides all three values (it floors the values, so you ‘lose’ the remainder), and then divides the remainder:

long n = x / 3
         + y / 3
         + z / 3
         + ( x % 3
             + y % 3
             + z % 3
           ) / 3

Note that the above sample does not always work properly when having one or more negative values.

As discussed with Ulugbek, since the number of comments are exploding below, here is the current BEST solution for both positive and negative values.

Thanks to answers and comments of Ulugbek Umirov, James S, KevinZ, Marc van Leeuwen, gnasher729 this is the current solution:

static long CalculateAverage(long x, long y, long z)
{
    return (x % 3 + y % 3 + z % 3 + 6) / 3 - 2
            + x / 3 + y / 3 + z / 3;
}

static long CalculateAverage(params long[] arr)
{
    int count = arr.Length;
    return (arr.Sum(n => n % count) + count * (count - 1)) / count - (count - 1)
           + arr.Sum(n => n / count);
}