from typing import List


def calculateVoltageDifference(adapters: List[int]) -> int:
   """
   Given a list of adapters, calculate product of 1-volt and 3-volt diffs
   """
   oneDiff: int = 0
   threeDiff: int = 1 # your phone adapter's diff
   prev: int = 0

   for i in range(len(adapters)):
      diff: int = abs(prev - adapters[i])
      if diff == 1:
         oneDiff += 1
      elif diff == 3:
         threeDiff += 1
      else:
         continue
      prev = adapters[i]
   
   return oneDiff * threeDiff