How many ways are there to choose two distinct positive integers totaling N, disregarding the order?
n=int(input())
if n%2==0:
  print(n/2-1)
else:
  print((n-1)/2)
n=int(input())
if n%2==0:
  print(int(n/2)-1)
else:
  print(int((n-1)/2))
