input: Develop a python function to determine the highest achievable value for a specified periodic function. Given three integers A, B, and N, the goal is to compute the maximum potential value of floor(A * x / B) – A * floor(x / B) where x is a non-negative integer not exceeding N. Note that floor(T) represents the largest integer that is less than or equal to the real number T.
  assert floor_Max(11,10,9) == 9
  assert floor_Max(5,7,4) == 2
  assert floor_Max(2,2,1) == 1
output:     
      max_value = 0
      for x in range(N + 1):
          current_value = (A * x // B) - A * (x // B)
          if current_value > max_value:
              max_value = current_value
      return max_value
  