input: Write a python function to count the number of elements in an array that are greater than a given target.
  assert countGreaterThan([7, 8, 4, 2, 9], 5) == 3
  assert countGreaterThan([1, 2, 3, 4, 5], 3) == 2
  assert countGreaterThan([10, 15, 20, 25], 17) == 2
output: def countGreaterThan(arr, target):
      count = 0
      for num in arr:
          if num > target:
              count += 1
      return count