for (int i = 0; i < nums.Length - 1; i += 3)
{
sums[sumsIndex] = int.Parse(nums[i]) + int.Parse(nums[i + 1] + int.Parse(nums[i + 2]));

sums[sumsIndex] = sums[sumsIndex] / 4;

sumsIndex++;
}
int diff = 0;
for (int j = 0; j < sums.Length - 1; j++)
{
if (Math.Abs(sums[j] - sums[j + 1]) > diff)
{
diff = Math.Abs(sums[j] - sums[j + 1]);
}