a = int(input())
if a % 2 == 1:
  print((a+1)/2/a)
else:
  print(0.5) a = int(input()) a int(input()) int input() input if a % 2 == 1:
  print((a+1)/2/a)
else:
  print(0.5) a % 2 == 1 a % 2 a 2 1 print((a+1)/2/a) print (a+1)/2/a (a+1)/2 a+1 a 1 2 a print(0.5) print 0.5 a = int(input()) int(input()) a
a = int(input())
if a % 2 == 1:
  print((a+1)/2/a)
else:
  print(0.5)