n=int(input())
if n%2==0:print(0.5)
else:print((n//2+1)/n) n=int(input()) n int(input()) int input() input if n%2==0:print(0.5)
else:print((n//2+1)/n) n%2==0 n%2 n 2 0 n=int(input()) int(input()) n
n=int(input())
if n%2==0:print(0.5)
else:print((n//2+1)/n)