#!/usr/local/bin/python2.7


   def main():

       total = 0;

       with open("day1.txt", 'r') as f:

          lines = f.readlines()

          for x in lines:
              values = int(x)

              while values / 3 - 2 >= 0:
                  new_values = ((values / 3) - 2)
                  values = new_values
                  total += values
          print(total)


  if __name__ == "__main__":
      main()