n=float(input())
if n%2==0:
  print(float(1/2))
else:
  print((n+1)/(2*n)) n=float(input()) n float(input()) float input() input if n%2==0:
  print(float(1/2))
else:
  print((n+1)/(2*n)) n%2==0 n%2 n 2 0 print(float(1/2)) print float(1/2) float 1/2 1 2 print((n+1)/(2*n)) print (n+1)/(2*n) n+1 n 1 2*n 2 n n=float(input()) float(input()) n
n=float(input())
if n%2==0:
  print(float(1/2))
else:
  print((n+1)/(2*n))