Write a Python program for finding the maximum of 3 numbers.
4, 7, 6
def max_of_three(a, b, c):
  if (a > b) and (a > c):
    greatest = a
  elif (b > a) and (b > c):
    greatest = b
  else:
    greatest = c
  return greatest

print("Max is: ", max_of_three(4, 7, 6))